Endocrine Flashcards
1
Q
What is the most common cause of hypothyroidism in the UK?
A
Hashimoto’s thyroiditis
2
Q
Which of the autoimmune hypothyroidisms present with a goitre?
A
Hashimoto’s thyroiditis (due to lymphocytic and plasma cell infiltration)
3
Q
What is the most common cause of hypothyroidism worldwide?
A
Iodine deficiency
4
Q
What are the effects of hypothyroidism on the body and how do these manifest?
A
Decrease in basal metabolic rate leads to decreased oxygen and substrate consumption, which causes:
- Apathy and slowed cognition - depression and dementia like symptoms
- Skin dryness and alopecia
- Increased LDLs and triglycerides
- Cold intolerance
Decreased sympathetic activity causes:
- Decreased sweating
- Cold skin due to decreased blood flow
- Constipation due to decrease GI motility
- Bradycardia
Hyperprolactinaemia - increased prolactin production is stimulated by TRH, which supresses LH, FSH, GnRH, testosterone but stimulates breast tissue growth
Myxoedema - due to accumulation of glycosaminoglycans within the reticular layer of the dermis
5
Q
What are the signs on examination of hypothyroidism (remember the mnemonic)?
A
BRADYCARDIC
Bradycardia Reflexes relax slowly (Woltman sign) Ataxia Dry thin hair and skin Yawning Cold Ascites + non-pitting oedema Round puffy face Defeated demeanour Ileus Cystic fibrosis
6
Q
What is the treatment for hypothyroidism?
A
Levothyroxine (synthetic T4 - which is then peripherally converted to the active T3)
7
Q
What is the main contraindication of levothyroxine?
A
Ischaemic heart disease
8
Q
What would TFTs of primary hypothyroidism look like?
A
TSH = high (compensatory) T4/T3 = low
9
Q
What would TFTs of secondary hypothyroidism look like?
A
TSH = normal or low if there is a lack from pituitary T4/T3 = low
10
Q
What causes secondary and tertiary hypothyroidism?
A
Secondary = pituitary disorders
Tertiary = hypothalamic disorders causing a deficiency of TRH (thyrotropin-releasing hormone)
11
Q
What is the most common cause of hyperthyroidism?
A
Grave’s disease
12
Q
What is the pathophysiology of Grave’s disease?
A
Autoimmune disease causes IgG antibodies to bind to TSH receptors, causing thyroid enlargement and increased hormone production
13
Q
Aside from Grave’s disease, what else can cause hyperthyroidism?
A
Toxic multinodular goitre
Toxic adenoma = solitary nodule producing T3 and T4
Ectopic thyroid tissue - metastatic follicular thyroid cancer
14
Q
What are the classic symptoms of hyperthyroidism?
A
Weight loss but increased appetite Insomnia Heat intolerance Sweating Diarrhoea Tremor Anxiety or psychosis Palpitations
15
Q
What signs would you see/feel in the hands with hyperthyroidism?
A
Palmar erythema Acropachy - painful finger swelling Sweaty palms Fine tremor Fast/irregular pulse
16
Q
What signs do you see in the eyes in Graves disease?
A
Lid lag
Lid retraction
Exophthalmos
17
Q
What is the main drug treatment for hyperthyroidism?
A
Block and replace therapy
Give carbimazole and thyroxine simultaneously
18
Q
Why is it better to do the block and replace therapy rather than just give carbimazole?
A
Reduces risk of iatrogenic hypothyroidism
19
Q
What are some dangerous side effects of carbimazole?
A
Neutropenia (agranulocytosis) which can lead to neutropenic sepsis
20
Q
What risk is there during a thyroidectomy and what would it cause?
A
Damage to laryngeal nerve
Cause a hoarse voice
21
Q
What can be used to destroy the thyroid gland to treat hyperthyroidism?
A
Radioiodine (iodine 131) given as a drink
22
Q
What is the risk of giving radioiodine?
A
Thyroid storm
23
Q
How does a thyroid storm present?
A
Severe hyperthyroidism:
- Fever
- Agitation
- Confusion
- Coma
- AF
- Diarrhoea + vomiting
24
Q
What are TFTs like in hyperthyroidism?
A
TSH = low (suppressed)
T4 + T3 = high
25
What drug can cause both hypo and hyperthyroidism?
Amiodarone
| It has iodine in it
26
How can you test to see if a neck lump is a goitre?
Ask patient to drink some water and swallow. A goitre will move up.
Then ask the patient to stick their tongue out. A goitre will not move but a thyroglossal cyst will.
27
What is Cushing's syndrome compared to Cushing's disease?
Cushing's syndrome is the clinical state produced by chronic glucocorticoid excess
Cushing's disease is excessive ACTH from the pituitary - usually a pituitary adenoma
28
What is the main cause of Cushing's syndrome?
Excess oral steroids
29
Aside from Cushing's disease, what is another ACTH-dependent cause of Cushing's syndrome?
Ectopic ACTH tumours e.g. small cell lung cancer
The classical symptoms of Cushing's are absent in this one
30
What does a Cushing's person look like?
* Moon face
* Acne
* Buffalo hump
* Cataracts
* Psychosis, depression, sleep disturbance
* Truncal obesity
* Abdominal striae
* Muscle/tendon wasting - recurrent Achilles tendon rupture
* Skin thinning
* Hirsutism
* Gonadal dysfunction - erectile dysfunction, irregular periods
* Hypertension
31
What condition are people with Cushing's at risk of?
Diabetes
32
What is the first-line screening test (after establishing a raised plasma cortisol) for Cushing's? What conditions can cause false positives?
Overnight low-dose dexamethasone suppression test
- give 1mg dexamethasone at midnight
- do serum cortisol at 8am
- normally, cortisol suppresses to <50nmol/L but in Cushing's there would be no suppression
- False positives are seen in depression, obesity, alcohol excess, inducers of liver enzymes
33
What is an alternative screening test to the overnight dexamethasone suppression test? What conditions can cause false positives?
24 hour urinary free cortisol
- 3 collections
- also measures creatinine excretion
- diagnosed in 2+ collections measure cortisol excretion as >3 times the lab upper limit of normal
- false positives occur in pregnancy, anorexia, exercise, psychoses, alcohol
34
What is the normal circadian rhythm for cortisol?
Lowest at midnight
| Highest early in the morning
35
How can you show that there is a loss of the normal circadian rhythm in Cushing's?
Midnight cortisol levels
- take bloods at midnight during sleep
- shows increased cortisol at midnight (when it should be at lowest)
36
Apart from oral steroids, what are some other ACTH-independent causes of Cushing's?
- Adrenal adenoma
| - Adrenal nodular hyperplasia
37
What test can you do to localise the cause of Cushing's?
Serum ACTH
- if it is undetectable, it is likely to be an adrenal tumour
- if it is raised, it is an ACTH-dependent cause (Cushing's disease or ectopic ACTH production)
38
How do you distinguish between a pituitary cause or ectopic ACTH producing cause of Cushing's?
High dose dexamethasone suppression test - there is a greater than 90% reduction in urinary cortisol in pituitary adenoma
39
What drugs can be used to lower cortisol levels?
Metyrapone - most commonly used
| Ketoconazole
40
If the source of Cushing's is unlocateable, what surgical treatment would you do?
Bilateral adrenalectomy
41
What is the main complication of a bilateral adrenalectomy?
Nelson's syndrome = increased skin pigmentation (ACTH reacts with melanin receptors) and ACTH-producing pituitary adenoma
42
Name an adrenolytic drug and what is it used for?
Mitotane
| Used for adrenal adenoma/carcinoma
43
What are the two different types of pituitary adenoma and what is the most common of each?
Secretory pituitary adenoma - prolactinoma
Non-secretory pituitary adenoma - gonadotroph adenoma
44
How does a growth hormone-producing tumour in children or adults?
```
Children = gigantism
Adults = acromegaly (increased sweating, headaches, hands and feet enlargement)
```
45
What visual defects do you get from a pituitary adenoma and why?
Bilateral temporal hemianopia due to compression of the optic chiasm
46
What cranial nerve palsies can occur due to a pituitary adenoma? Why? And how does it present?
CN III, IV, VI due to pressure on the cavernous sinus Presents as a squint causing diplopia
47
Describe a headache secondary to pituitary adenoma
Worse on waking
Retro-orbital
Bitemporal
48
What other condition can be caused by pituitary adenoma?
Diabetes insipidus (which is not related to diabetes mellitus).
Characterised by polydypsia and polyuria
It is due to reduced ADH secretion from the posterior pituitary
49
What is an MRI defining in a pituitary adenoma?
Whether there is intra or supra-sellar extension
Size of the pituitary gland
50
When treating hypothyroidism secondary to hypopituitarism, what must you give before levothyroxine and why?
Steroids because thyroxine could precipitate and Addisonian crisis (=adrenal crisis)
51
What normally causes parathyroid hormone to be secreted?
Low calcium levels
52
How does PTH increase calcium levels and decrease phosphate levels?
1. Increases osteoclast activity, which releases calcium and phosphate from bones
2. Increases calcium reabsorption + decreases phosphate reabsorption from kidney
3. Increases vitamin D3 production
53
Who is primary hyperparathyroidism most common in ?
Post-menopausal women
54
What is the main cause of primary hyperparathyroidism?
Solitary adenoma of the parathyroid gland
55
What gene is primary hyperparathyroidism sometimes associated with?
MEN1 or MEN2 (multiple endocrine neoplasia)
56
What 4 steps should you take if someone presents with hypercalcaemia in order to find the cause?
1. Look for drug causes e.g. lithium, thiazides
2. Repeat plasma albumin-adjusted calcium levels
3. Check renal function
4. Measure PTH
57
What cancer is MEN2 associated with?
Thyroid cancer
58
How do you treat primary hyperparathyroidism?
Increase fluid intake
| Parathyroidectomy to remove the respective gland
59
What are the calcium levels like in secondary hyperparathyroidism? Why?
Normal or low
| The hyperparathyroidism occurs because the parathyroid glands become hyperplastic after longterm hypocalcaemia
60
What are the 2 main causes of secondary hyperparathyroidism?
Chronic kidney disease - most common cause
| Vitamin D deficiency
61
What drug can be used to treat secondary hyperparathyroidism?
Cinacalcet - it increases the sensitivity of parathyroid cells to calcium, therefore decreasing PTH secretion
62
What are the calcium levels like in tertiary hyperparathyroidism and why?
High
Due to prolonged secondary hyperparathyroidism, the glands act autonomously so they produce excessive PTH even after hypocalcaemia is fixed
63
What drugs can cause hypoglycaemia?
```
Insulin
Sulphonylureas
GLP-1 analogues
DPP-4 inhibitors
Beta-blockers
Alcohol
```
64
How can you distinguish between the presence of exogenous and endogenous insulin?
High insulin AND high C-peptide and proinsulin = Endogenous production
High insulin AND low C-peptide and proinsulin = Exogenous administration
65
What can be given in mild hypoglycaemia (i.e. they are still conscious)?
Glucogel
15-20g glucose tablets
Sweets
Fruit juice
66
What can be given in severe hypoglycaemia (i.e. they are not conscious)?
150ml 10% dextrose or 75ml 20% dextrose IV
| 1mg/kg glucagon IM if no IV access
67
In which patients would IM glucagon not be effective?
Acute alcohol - alcohol blocks gluconeogenesis
Patients with depleted glycogen stores:
- Adrenal insufficiency
- Insulinoma
- Anorexic pts - chronic starvation
68
What is the triad of Grave's disease?
1. Diffuse goitre
- Smooth, uniformly enlarge goitre
- Bruit heard at superior poles of lobes due to increased vascularity
2. Ophthalmopathy
- Exophthalmos
- Lid retraction
- Diplopia
3. Pretibial myxoedema
- Non-pitting oedema and firm plaques on the anterior and lateral aspects of legs
69
What thyroid antibodies are specific to Grave's disease?
TRAbs (TSH receptor antibodies)
70
What is the triad of Graves disease?
1. Diffuse goitre
2. Ophthalmopathy
3. Pretibial myxoedema
71
Describe the goitre in Graves disease
Smooth, uniformly enlarged goitre
72
What antibodies can be tested for in Graves disease?
TRAbs (TSH receptor antibodies) - specific to Graves and would be raised
Anti-TPO and anti-Tg would also be raised but are non-specific
73
What imaging can be done to diagnose Graves disease?
Thyroid scintigraphy
- Shows a diffuse uptake of radioactive iodine (123-I)
- Contraindicated in pregnancy
Thyroid ultrasound with colour Doppler
- For pregnant women
- Shows enlarged, hypervascular thyroid
74
What medication provides symptomatic relief in hyperthyroidism?
Propanolol
75
What are the symptoms of hypercalcaemia as seen in primary hyperparathyrodism?
* CVD - hypercalcaemia leads to the calcification of arteries and myocardium
* Renal stones
* Polyuria and polydipsia
* Bone, muscle and joint pain
* Pseudogout
* Osteitis fibrosa cystic (cyst-like brown tumours)
* Weight loss
* Constipation
* Peptic ulcers (hypercalcaemia leads to high levels of gastrin which stimulates stomach acid production)
* Pancreatitis
* Psychological disturbances
76
What is Addison's disease?
Primary adrenocortical insufficiency
A condition where the adrenal cortex has been destroyed so there is a deficiency of glucocorticoid (cortisol) and mineralocorticoid (aldosterone)
77
What are the most common causes of Addison's in the UK and worldwide?
UK - autoimmune
| TB - worldwide
78
What causes secondary adrenocortical insufficiency?
Sudden discontinuation of steroids of physiological stress (infection, trauma, surgery) during prolonged steroid therapy
Hypopituitarism
79
How does hypopituitarism cause secondary adrenocortical insufficiency?
There is a decrease in ACTH release which leads to decreased endogenous cortisol production
80
What causes tertiary adrenocortical insufficiency?
Conditions that decrease corticotropin-releasing hormone (CRH) production
- Sudden discontinuation of steroid therapy
- Hypothalamic dysfunction (trauma, mass, haemorrhage, anorexia)
81
What three hormones are produced by the adrenal cortex?
1. Androgen
2. Cortisol
3. Aldosterone
82
How does low androgen present?
* Loss of libido
| * Loss of axillary and pubic hair
83
How does low cortisol present?
* Weight loss
* Fatigue, lethargy
* GI symptoms - nausea, vomiting, diarrhoea
* Orthostatic hypotension
* Hypoglycaemia
84
How does low aldosterone present?
* Hypotension
| * Salt craving
85
Why do you get orthostatic hypotension with low cortisol?
Glucocorticoids play an important role in catecholamine-induced vasoconstriction and myocardial contractility
86
In Addison's disease there is raised ACTH; how does this present and why?
Hyperpigmentation
Increased ACTH - leads to increased POMC production (in order to boost ACTH production), which increases melanocyte-stimulating hormone, causing hyperpigmentation of the skin
87
Which of the adrenal hormones is not affected in secondary and tertiary adrenal insufficiency?
Aldosterone synthesis is not affected because mineralocorticoid production is controlled by RAAS, not by ACTH
88
How does an adrenal crisis present?
* Hypotension, shock
* Reduced GCS
* Fever
* Vomiting and diarrhoea
* Severe abdominal pain that resembles peritonitis
89
What are the U+Es like in Addison's disease?
Hyponatraemia, hyperkalaemia - due to aldosterone
High urea
Mildly high calcium
90
What would a VBG/ABG show in Addison's?
Metabolic acidosis
| Hypoglycaemia - due to cortisol
91
What is the best initial test for diagnosing low cortisol?
Morning serum cortisol levels
OR
Morning serum ACTH level (short synacthen test) - ACTH is high in primary insufficiency but low in secondary
92
What is the confirmatory test for low cortisol? What does it involve?
ACTH stimulation test
- Measurement of serum cortisol before and 30 minutes after administration of ACTH
- In primary there would not be a sufficient rise in cortisol; in secondary/tertiary there would be a normal rise in cortisol
93
What tests can be done to diagnose low aldosterone?
* High plasma renin concentration
| * Low urine aldosterone levels
94
What test is diagnostic of low androgen from the adrenal glands?
Low DHEA-S - DHEA-S is only synthesised in the adrenal glands (note that low adrogen can be caused by hypogonadism too but would have normal DHEA-S)
95
What investigations allow you to distinguish between primary, secondary and tertiary adrenal insufficiency?
* Serum ACTH levels distinguish between primary and secondary/tertiary adrenal insufficiency
* CRH stimulation test is used to distinguish between secondary and tertiary adrenal insufficiency
96
What is the treatment of adrenocortical insufficiency?
Hydrocortisone for glucocorticoid replacement - administer in 2-3 doses daily to mimic natural diurnal rhythm
Fludrocortisone for mineralocorticoid replacement - only required in primary
97
What are the rules for patients on long-term steroid therapy?
* Carry a steroid card on their person
* Have a medic-alert bracelet
* If they have any illness they should double their regular steroid medication dose
98
How is an Addisonian crisis managed?
1. Fluid resuscitation
2. IV hydrocortisone 100mg TDS
3. IV 50% dextrose
4. Swap back to oral steroids after 3 days
5. Fludrocortisone if caused by adrenal problem
99
Which cancers most commonly cause hypercalcaemia of malignancy?
* Non-small cell lung cancer
* Multiple myeloma
* Breast carcinoma
* Renal cell carcinoma
* Head and neck cancers
100
What is seen on an ECG in hypercalcaemia?
```
Bradycardia
Short QT interval
Wide T waves
Prolonged PR interval
BBB
Arrhythmias
```
101
What is included in a bone profile?
```
Calcium
Phosphate
Albumin
Total protein
ALP
```
102
What blood levels indicate hypercalcaemia of malignancy rather than primary hyperparathyroidism?
* Low albumin
* Low chloride
* Alkalosis
* Low potassium
* High phosphate
* High ALP
103
What is the management of hypercalcaemia?
1. IV 0.9% saline 1L every 4 hours for 24h then every 6 hours for 48-72h
2. Zolendronic acid 4mg IV or IV pamidronate
3. Salmon calcitonin (S/C or IM) and corticosteroids (prednisolone PO)
104
What are the most common causes of hypoparathyroidism?
Postoperative due to injury of the parathyroid glands during thyroidectomy/parathyroidectomy
Autoimmune - second most common
105
How does acute hypoparathyroidism present and what signs can be found on examination?
Hypocalcaemia causes hyperexcitable nerves
Tetany
Chvostek sign - tapping the facial nerve on the cheek causes contraction of facial muscles
Trousseau sign - carpal spasm on inflation of BP cuff
106
How is hypoparathyroidism treated?
Calcium and vitamin D supplementation (AdCal)
107
What are the most common and second most common types of thyroid cancer?
1. Papillary carcinoma (70%)
| 2. Follicular (10-20%)
108
What gene is medullary carcinoma of the thyroid associated with?
MEN2
109
How can thyroid cancer present?
* Firm, painless thyroid nodules
* Hoarse voice
* Horner syndrome
* Dysphagia
110
What type of thyroid cancer has an extremely poor prognosis?
Anaplastic (undifferentiated) carcinoma
111
What is the management for papillary and follicular thyroid carcinomas?
Thyroidectomy (hemi/total depending on size)
Radioiodine given post-surgery to destroy remaining disease tissue and locate metastases
After surgery and radioiodine therapy, even if there is functioning thyroid tissue left, patients may be given levothyroxine to suppress TSH secretion, which reduces risk of stimulating remaining malignant tissue and helps monitor the presence of any further carcinoma as high levels of T3/T4 present in the blood at this stage hint at further disease presence
112
What is a goitre?
Goitre = enlarged palpable thyroid gland, which moves on swallowing
113
What can cause a multinodular goitre?
Toxic goitre
- Grave's disease
- Toxic multinodular goitre
Hypothyroid goitre
- Hashimoto's
- Congenital
Endemic - iodine deficiency
114
What are the different grades of goitre on palpation of the thyroid?
Grade 0 - no goitre palpable or visible
Grade 1 - palpable goitre, not visible when neck is in normal position
Grade 2 - swollen neck and palpable goitre
115
What is the best imaging modality of thyroid?
USS - can determine size, nodules, consistency, vascularity
116
What is the difference between simple and multinodular goitres in terms of thyroid hormones?
Simple goitres are associated with normal thyroid hormone levels
Multinodular goitres secrete autonomously and can cause hyperthyroidism
117
How are non-toxic goitres managed?
* No treatment required if patient is asymptomatic
| * Schedule follow-ups for possible thyroid function issues and obstructive symptoms
118
How are large goitres managed?
* Surgery to avoid obstructive complications
| * Radioiodine therapy if unsuitable surgical candidate
119
What is a thyroid nodule?
An abnormal growth within the thyroid gland
120
Thyroid nodules can be benign (95%) or malignant (5%). What is the most common thyroid nodule? Give examples of other thyroid nodules
Follicular adenoma - most common
Thyroid adenomas
- Follicular adenoma
- Toxic adenoma
- Papillary adenoma
Thyroid cysts
Hashimoto thyroiditis
121
What are the first line investigations for a suspected thyroid nodule?
TSH levels
| USS of neck
122
What are the criteria for carrying out fine needle aspiration of a thyroid nodule?
- Solid nodule with oval shape/irregular border/calcifications that are 1+cm in diameter
- Nodules <1cm in patients with risk factors for malignancy
- Large thyroid nodules (>1.5-2cm) even if they appear benign
123
What is hashitoxicosis, what is it caused by and how does it present?
Transient hyperthyroidism due to follicular rupture of hormone-containing thyroid tissue
Irritability, heat intolerance, diarrhoea
124
What is De Quervain thyroiditis also called?
Subacute granulomatous thyroiditis
125
What is De Quervain thyroiditis usually preceded by?
Viral infections e.g. mumps, coxsackie, influenza, adenovirus
126
Go through the triphasic response of De Quervain thyroiditis?
1. Thyrotoxic phase (2-8 weeks) - caused by damage to follicular cells and release of thyroid hormones causing features of hyperthyroidism
2. Hypothyroid phase (2-8 weeks) - caused by depletion and impaired synthesis of thyroid hormones due to damage of follicular cells
3. Euthyroid phase: thyroid function recovers and pathological changes no longer visible on the gland
127
What should you not give in the thyrotoxic phase of De Quervain thyroiditis?
Do not give carbimazole in thyrotoxic phase because it target the synthesis of thyroid hormones and the thyrotoxic phase is caused by damage to follicular cells and release of thyroid hormones
128
What investigation assesses visual field defects?
Perimetry
129
What is the first line treatment of prolactinomas?
Dopamine agonists (cabergoline 0.25-1mg weekly or twice weekly) to shrink the pituitary adenoma
130
What is the second line treatment of prolactinomas?
Transphenoidal hypophysectomy (resection of pituitary gland) +/- adjuvant radiotherapy
131
How are non-secretory pituitary microadenomas managed?
No treatment, just follow-up, they often cease growing on their own
132
What is the order in which anterior pituitary hormones are affected in hypopituitarism?
* GH - muscle and bone
* FSH - ovary
* LH - testes
* Prolactin - breast
* TSH - thyroid
* ACTH - kidney + adrenals
133
What is the most common cause of hypopituitarism?
Pituitary adenoma
134
Why is the pituitary vulnerable to ischaemia?
It receives blood supply from relatively low-pressure arterial system
135
What syndrome causes pituitary apoplexy?
Sheehan syndrome: postpartum necrosis of pituitary gland following postpartum haemorrhage
136
What syndrome causes a congenital deficiency of hypothalamic hormones?
Kallman syndrome - GnRH deficiency
137
How does GH deficiency present?
Weight gain
Weakness
Depression
138
How does FSH/LH deficiency present in males/females?
```
Females…
• Oligomenorrhoea or amenorrhoea
• Reduced fertility
• Reduced libido
• Osteoporosis
• Breast atrophy
• Dyspareunia
```
```
Males…
• Erectile dysfunction
• Low libido
• Low muscle bulk
• Hypogonadism
```
139
How do you test for GH deficiency?
IGF-1 (insulin-like growth factor) - decreased
140
Why are GH levels an inaccurate test of GH deficiency?
GH is secreted in pulsatile manner
141
What further test for GH deficiency can be done in a specialist centre and what does it assess?
Assesses the adrenal and GH axes
Insulin tolerance test
- IV insulin to induce hypoglycaemia and increase in cortisol and GH secretion
- It is a fasting test
- Measure cortisol and GH levels when glucose < 2.2mmol/L
- Normal GH >20 and cortisol >550
142
How do you test for FSH/LH deficiency?
GnRH stimulation test
- Decreased LH in males
- Decreased FSH and LH in females
Serum DHEA and testosterone levels between 8am and 10am - low
Oestradiol levels - low
143
What is pheochromocytoma?
Rare tumour of adrenal glands, which releases catecholamines (adrenaline and noradrenaline)
144
What do pheochromocytoma tumours arise from?
Tumours arise from chromaffin cells, which are derived from the neural crest
145
Where are most pheochromocytoma tumours located?
90% are located in the adrenal medulla - the adrenal medulla is considered a modified sympathetic ganglion, which is innervated by sympathetic preganglionic neurons
146
What are the 5 Ps of pheochromocytoma?
1. increase blood Pressure
2. head Pain
3. Perspiration
4. Palpitations
5. Pallor
147
What is the best initial test to investigate pheochromocytoma?
Plasma metadrenaline and normetadrenaline test (metabolites of catecholamines) - best initial test, highly sensitive
148
What is the confirmatory test for pheochromocytoma?
24 hour urine metadrenalines and catecholamines - confirmatory test, highly specific
149
What would be found on 24 ABPM in pheochromocytoma?
Absence of BP drop overnight
150
What is the treatment for pheochromocytoma in the acute setting?
1. Phentolamine IV (short acting alpha blocker) - to initially control BP
2. Phenoxybenzamine (longer acting alpha blocker) - to control BP before surgery can be arranged
3. Labetolol (beta blocker) - can be used if patient has tachyarrhythmia but only AFTER alpha blockade
151
What is the definitive management of pheochromocytoma?
Adrenalectomy - 4-6 weeks after blood pressure has been controlled
152
What can occur during abdominal examination in pheochromocytoma?
Hypertensive crises can be triggered by palpation of the tumour on abdominal examination due to a massive release of catecholamines
153
What is Conn's disease?
Hyperaldosteronism
154
What is the main cause of hyperaldosteronism?
Adrenal adenoma (80%)
155
What is the effect of excess aldosterone on the kidneys?
Excess aldosterone acts on the distal renal tubule, resulting in retention of sodium and excretion of potassium and calcium
156
How does Conn's disease present?
* Polyuria
* Polydipsia
* Lethargy
* Headaches
* Osteoporosis
* Secondary hypertension - treatment resistant to multiple agents
157
What would U+Es show in hyperaldosteronism?
Hypokalaemia
| Hypernatraemia
158
What test confirms the diagnosis of hyperaldosteronism?
Aldosterone/renin ratio - ratio > 800 confirms diagnosis and prompts investigation for cause
159
How do you treat hyperaldosteronism?
Surgical resection of affected gland
Spironolactone (potassium-sparring diuretic)
160
What is the diagnostic criteria for HHS?
* Severe hyperglycaemia >=30mmol/L
* Hypotension
* Hyperosmolality - >320 mosmol/kg
161
How is blood osmolality calculated?
Glucose + urea + 2xNa
162
What is the management of HHS?
1. Fluid resuscitation - 0.9% sodium chloride :
a. 1L over 1-2 hours
b. 1L (+KCl) over 2-4 hours
c. 1L (+KCl) over 4-6 hours
d. 1L (+KCl) over 6-8 hours
e. 1L (+KCl) over 8-10 hours
2. Insulin at 0.05 units/kg/hour
- only if ketones >1mmol/L or glucose fails to fall
3. VTE prophylaxis - these patients are high risk due to dehydration
163
What are the two different types of diabetes insipidus?
Central diabetes insipidus - most common
Nephrogenic diabetes insipidus - rare
164
What is the pathophysiology behind diabetes insipidius?
Central diabetes insipidus - insufficient/absent hypothalamic synthesis or secretion of ADH from the posterior pituitary gland
Nephrogenic diabetes insipidus - defective ADH receptors in distal tubules and collecting ducts
ADH enables the integration of aquaporins in to the plasma membrane of collecting duct cells, leading to reabsorption of free water
Reduced ADH leads to dilute urine
165
What are some secondary causes of central diabetes inspidius?
Brain tumours - craniopharyngioma, cerebral mets from lung cancer and leukaemia/lymphoma
Neurosurgery - after resection of macroadenomas
Traumatic brain injury
Pituitary ischaemia e.g. Sheehan syndrome
Inflammatory conditions e.g. sarcoidosis
Infection e.g. meningitis
166
What drugs can cause nephrogenic diabetes insipidus?
Lithium
| Tetracyclines
167
How does diabetes insipidus present?
* Polyuria > 3L/day
* Nocturia
* Polydipsia
* Dehydration
168
What test is diagnostic of diabetes insipidus?
The 8 Hour Water Deprivation Test - the purpose of this test is to see if the kidneys persist in producing dilute urine despite dehydration, and then to localise the cause
169
What is the first line treatment for central diabetes insipidus?
Desmopressin - synthetic vasopressin without vasoconstrictive effects
170
What is the second line treatment for central diabetes insipidus?
Chlorpropamide - increases ADH secretion
171
What can be given to patients with lithium-induced NDI?
Amiloride - it blocks lithium entry through the Na+ channel
172
What are normal sodium levels?
135-145mmol/L
173
What levels indicate mild, moderate and severe hyponatraemia?
* Mild – 125 – 134 mol/L
* Moderate – 120-124 mmol/L
* Severe – <120 mol/L
174
What are the three types of hyponatraemia?
Hypovolaemic
Euvolaemic
Hypervolaemic
175
What can cause hypovolaemic hyponatraemia?
• Renal causes
- Diuretics - particularly thiazide diuretics
- Adrenal insufficiency (Addison's)
- Osmotic diuresis - low glucose and urea
- Nephropathy
• GI
- Vomiting and diarrhoea
- Pancreatitis
- Bowel obstruction
- Peritonitis
* Burns
* Rhabdomyolysis
* Excessive sweating
* Bleeding
176
What type of hyponatraemia does SIADH cause?
Euvolaemic hyponatraemia
177
What can cause SIADH?
CNS disturbances - infection, inflammation, trauma, psychosis
Malignancy - SCLC
Pain
Pulmonary disease - especially pneumonia
Drugs - SSRI, ecstasy, carbamazepine, opiates, MAOI
178
What causes hypervolaemic hyponatraemia?
* Heart failure
* Renal failure - nephrotic syndrome
* Liver failure
* Hyperglycaemia
179
At what sodium levels do symptoms start?
Na < 125 mmol/L
180
What are the symptoms of hyponatraemia?
* Confusion
* Lethargy
* Seizures
* Coma
* Muscle weakness
181
How do you manage SIADH?
1. Fluid restriction (up to 750ml/day) and treat underlying cause
2. ADH antagonists (e.g. tolvaptan, deomeclocycline)
3. Oral sodium and furosemide
182
If a patient with hyponatraemia is having seizures, what further management is required?
Hypertonic 3% sodium chloride in ICU
183
Why do you need to avoid rapid correction of hyponatraemia?
It can lead to osmotic demyelination syndrome (central pontine myelinosis) - brain was oedematous then extra Na+ influx causes water to go out of brain quickly leading to demyelination
