Case 10 Flashcards
1
Q
What findings suggest diabetes?
A
Fasting plasma glucose >7mmol/L
Random “ “ >11.1mmol/L
2hr glucose post 75g GTT >11.1
HbA1c > 6.5%
2
Q
How can diabetes be diagnosed?
A
Test once with symptoms
Test on 2 occasions if asymptomatic
3
Q
What are the common symptoms of diabetes?
A
Polydipsia (excessive thirst) Polyuria (production of large volumes of urine) Blurred vision Oral/ genital thrush Weight loss - type 1
4
Q
What shows impaired glucose tolerance?
A
Fasting blood glucose
5
Q
Who typically gets Type 1 diabetes and how do they present?
A
Slim 0.5 - 70 yo - median age is 12 Weight loss Rapid onset Most don't have a family history Prone to ketosis
6
Q
Differences between type 1 and 2 diabetes
A
Type 1: weight loss, rapid onset, diagnosis at 12yo, ketosis prone, common in caucasians
Type 2: chronic onset, diagnosis >40yo, don’t get ketosis but can get hyperosmolar hyperglycaemic state (HHS), more common than type 1, gestational diabetes predicts susceptibility
7
Q
What are the macrovascular complications of diabetes?
A
MI Acute coronary syndromes (NSTEMI, STEMI, unstable angina) Stoke Peripheral vascular disease Renal artery stenosis Heart failure Gut ischaemia
8
Q
What are the microvascular complications of diabetes?
A
Neuropathy
Retinopathy
Nephropathy
9
Q
Why is there usually absolute insulin deficiency in type 1 diabetes?
A
T cell mediated selective destruction of beta cells
10
Q
What happens when glucose levels fall below 4mM?
A
Autonomic symptoms - tremor, palpitations, sweating, hunger, anxiety
11
Q
What happens when glucose levels fall below 3mM?
A
CNS dysfunction
12
Q
What happens when glucose levels fall below 2mM?
A
Coma/ seizure
13
Q
What is neuroglycopenia?
A
Shortage of glucose in brain
Can present as confusion, fits, abnormal behaviour, unconsciousness
14
Q
How can the body increase glucose levels?
A
Adrenaline and glucagon stimulate glycogen conversion to glucose
Cortisol increases gluconeogenesis
Lactate e.g. from MI is converted to pyruvate by Krebs cycle, pyruvate is then used for gluconeogenesis
15
Q
What blood glucose level is considered hypoglycaemic?
A
Below 3.5 mM
16
Q
What causes death in DKA?
A
Cerebral oedema
Hypokalaemia
Underlying condition - sepsis, ARDS (acute resp distress syndrome), MI
17
Q
What is novorapid?
A
Short acting insulin
18
Q
What is levemir?
A
Long acting insulin
19
Q
What is the target bp for diabetics?
A
20
Q
What type of gland produces hormones then secretes them directly into the bloodstream? (not through ducts)
A
Endocrine
21
Q
What does low ACTH (adrenocorticotropic hormone) suggest?
A
Pituitary problem
22
Q
What does low cortisol suggest?
A
Adrenal gland damage
May have compensatory high ACTH to try to increase cortisol
23
Q
What stimulates cortisol secretion?
A
Hypothalamus secretes corticotrophin releasing hormone (CRH)
that causes the anterior pituitary to secrete ACTH (adrenocorticotropic hormone)
that causes the adrenal gland to secrete cortisol
24
Q
What is the cortisol level in Addison’s disease?
A
Low cortisol - insufficient
25
What is the cortisol level in Cushing's syndrome?
High cortisol - excess (cushioned person has excess fat)
26
When would be best to test for Addison's?
9am
Addison's is low cortisol, at 9am normal people should have high cortisol so if it's low you know it's addison's
(normally low at midnight - so don't test then)
27
When would be best to test for Cushing's?
Midnight
Cushing's is high cortisol, normal people should have low cortisol at midnight so if it's high you know it's Cushing's
(normally high at 9am so don't test then)
28
Name the layers of the adrenal cortex and what they produce
```
(GFR from capsule/outer to medulla/inner)
Glomerulosa - aldosterone
Fasciculata - cortisol
Reticularis - DHEA
(gears and full clutch = real driving)
```
29
What's Conn's syndrome?
Excess aldosterone
| Causes increased bp as more water reabsorbed
30
Explain what's going on in Addison's disease
Addison's is a primary adrenocortical insufficiency
Adrenal gland destruction/ dysfunction e.g. from metastatic disease
Causes deficiency in cortisol, androgen and mineralocorticoid production
ACTH is raised in aim to increase cortisol production
ACTH binds to skin melanocortin 1 receptors (MC1R) causing pigmentation
31
What may cause adrenal gland destruction/ dysfunction?
Autoimmune
TB - caseous necrosis of adrenal cortex
Metastatic disease
Systemic amyloidosis - deposits of amyloid in different tissues and organs
Fungal infections
Haemochromatosis - iron levels slowly build up over years, build up of iron in adrenal gland causes adrenal dysfunction
Sarcoidosis - granuloma development in different organs
32
What happens in secondary adrenal insufficiency?
Pituitary problem
Low cortisol (glucocorticoid) secondary to low ACTH
(low ACTH = no pigmentation)
Also reduced androgen secretion (DHEA)
As zonae fasciculata and reticularis atrophy
Most of the time, mineralocorticoids (aldosterone) secretion is normal
33
What are the levels of cortisol and ACTH in Addison's disease/ primary adrenal insufficiency?
Low cortisol
| High ACTH
34
What are the levels of cortisol and ACTH in secondary adrenal insufficiency?
Low ACTH
| Low cortisol
35
What causes secondary adrenocortical insufficiency?
Most commonly glucocorticoid (cortisol) administration
| Also hypothalamic/ pituitary tumours, surgery, radiotherapy, infection e.g. TB, inflammation from sarcoidosis
36
What are the general symptoms of adrenocortical insufficiency?
```
Weakness
Fatigue
Anorexia
Nausea/ vomiting
Weight loss
Hypoglycaemia
Sexual dysfunction
Amenorrhoea - weight loss/ chronic illness/ primary ovarian failure
Loss of axillary/ pubic hair in women - decreased androgen levels
Adrenal crisis
```
37
What are the symptoms of adrenocortical insufficiency more specific to primary adrenal insufficiency?
```
Those caused by mineralocorticoid (aldosterone) deficiency
Hyperkalaemia
Hyponatreamia
Hypotension - volume depletion
Dehydration
```
38
Why does increased levels of ACTH lead to hyperpigmentation?
ACTH is derived from pro-opiomelanocortin (POMC) which is also a precursor for melanocyte stimulating hormone (MSH)
So if you make more POMC (in order to make more ACTH), you’ll make more MSH
39
How can adrenal insufficiency be diagnosed?
Low cortisol
| and failure to increase plasma cortisol level on ACTH administration
40
How can primary adrenal insufficiency be distinguished from secondary?
Primary - increased ACTH
| Secondary - decreased ACTH
41
What causes Cushing's syndrome?
Taking glucocorticoid drugs
| Tumour (pituitary/ hypothalamic/ lungs - ectopic ACTH syndrome) that produces cortisol/ ACTH
42
Which cells secrete adrenaline and noradrenaline?
Chromaffin cells in adrenal medulla
43
Name 3 catecholamines
Dopamine, adrenaline and noradrenaline
44
What's pheochromocytoma?
Rare tumour of adrenal gland tissue
| Results in excess release of adrenaline and noradrenaline
45
What are the signs and symptoms of pheochromocytoma?
```
(The 5 Ps)
Pressure - hypertension
Pain - headache
Perspiration
Palpitation
Pallor
The classical triad is pain, perspiration and palpitations
```
46
What can pituitary tumours cause in terms of compression?
Compression of optic chiasm - bitemporal hemianopia
| Compression of cranial nerves - cranial nerve palsies
47
What are the 2 releasing hormones produced in the anterior pituitary that have inhibitory effects?
Somatostatin inhibits GH
| Dopamine inhibits prolactin
48
What are the FSH and LH levels after the menopause?
High as no oestrogen so no negative feedback inhibition
49
What connects the hypothalamus to the anterior pituitary?
Parvocellular neurosecretory cells - small neurones within paraventricular nucleus of hypothalamus thats axons project to median eminence
Releasing hormones released from the nerve terminals into capillaries of pituitary portal system
50
What effect does alcohol have on ADH?
Alcohol suppresses ADH
51
What does a deficiency of FSH cause?
Infertility
52
What does a deficiency of LH cause?
Hypogonadism
Women - amenorrhoea, oligomenorrhoea (light/ infrequent)
Men - reduced sperm count
53
What does a deficiency of GH cause?
In children - short stature
| In adults - abnormal body composition, reduced muscle mass
54
What is FT4?
Free thyroxine
55
What is FT3?
Free triiodothyronine
56
How can T4 be converted to T3?
F4 is deiodinated to T3
57
What is thyroid hormone production dependent on?
Adequate iodine intake - iodine deficiency can cause hypothyroidism
58
What can cause hypothyroidism?
Hashimoto thyroiditis - autoimmune disease causing primary thyroid failure
Iodine deficiency
59
What are the symptoms of hypothyroidism?
```
Fatigue
Weight gain
Cold intolerance
Depression
Menstrual irregularities
Constipation
Joint pain
Muscle cramps
Infertility
```
60
What are the signs of hypothyroidism?
```
Hoarseness
Hypothermia
Periorbital puffiness
Delayed relaxation of ankle jerks
Loss of outer 1/3 of eyebrow
Cool, rough, dry skin
Non-pitting oedema
Bradycardia
Peripheral neuropathy
```
61
What is the end stage of hypothyroidism is treatment is insufficient?
Myxoedema coma
| Person becomes increasingly withdrawn, lethargic, sleepy and confused then slips into a coma
62
What are the TSH and T4 levels in primary hypothyroidism?
(thyroid problem)
Low FT4
High TSH
63
What are the TSH and T4 levels in secondary hypothyroidism?
(low thyroid hormones secondary to pituitary problem)
Low T4
Low (or normal) TSH
64
What are the results expected from U+E and LFT in hypothyroidism?
Hyponatraemia
| Raised bilirubin, ALT (alanine transaminase), LDH (lactate dehydrogenase) and creatinine kinase
65
What does euthyroid mean?
Normally functioning thyroid gland
66
How can hypothyroidism be distinguished from euthyroid sick syndrome?
Euthyroid sick syndrome will have
Low T3
Normal/ low TSH (high in primary hypothyroidism)
Normal FT4 (low in hypothyroidism)
67
What are the symptoms of hyperthyroidism?
```
Excessive sweating
Heat intolerance
Increased bowel movements
Tremor
Palpitations
Weight loss with increased appetite
Fatigue
Poor concentration
Increased anxiety, irritability
Irregular/ scant periods
```
68
What would confirm hyperthyroidism in a thyroid function test?
Elevated FT4
Low TSH (however hyperthyroidism secondary to pituitary adenoma will have elevated TSH)
(T4 converted to T3 so T3 will also be elevated)
But check T3 to rule out T3 toxicosis (hyperthyroidism caused by excessive T3, high T3 but normal T4)
69
What causes hyperthyroidism?
Most commonly - Graves disease
Then
toxic multinodular goitre and solitary toxic nodular goitre
70
What causes Graves disease?
Autoimmune thyroid-stimulating antibodies
71
What are the clinical manifestations of Graves disease?
Small diffuse goitre
Ophthalmopathy i.e. proptosis (bulging eyes), conjunctivitis, oedema, erythema (redness), lid lag, upper eyelid retraction
72
How is Graves disease treated?
Antithyroid medications
Radioactive iodine
Thyroidectomy
73
How is toxic multinodular goitre and solitary adenomas treated?
Radioiodine therapy
74
What can be used in palliative treatment of mild hyperthyroidism?
Beta-blockers most commonly propanolol
75
What are the TSH, T4 and T3 levels in hyperthyroidism?
Low TSH
High T4
High T3
76
What are the TSH, T4 and T3 levels in T3 toxicosis hyperthyroidism?
Low TSH
Normal T4
High T3
77
How can the cortisol response to ACTH be tested?
Synacthen stimulation test
| Synacthen is a synthetic ACTH
78
What are the 2 types of humor (fluid/ semifluid substance) in the eye?
```
Aqueous humour (in front of lens, freely flowing)
Vitreous humor (behind lens, gelatinous)
```
79
What affects intraocular pressure?
The balance between aqueous humor formation and reabsorption
80
What secretes aqueous humor?
Ciliary processes
81
How does aqueous humor move enter anterior chamber from the posterior chamber?
Through the pupil
82
Explain the drainage of aqueous humor
It moves through the trabecular meshwork
Enters canal of Schlemm
Empties into collector channels into episcleral veins
(Also a uveoscleral pathway of drainage but trabecular meshwork does most of the drainage)
83
What is the conjunctiva of the eye?
Mucous membrane covering the front of the eye and line the inside of eyelids
84
Generally describe the blood supply to the eye
Internal carotid artery
Ophthalmic artery
Central retinal artery and ciliary arteries
85
Which artery supplies the retina?
Central retinal artery
86
Which artery supplies the choroid?
Short posterior artery
87
What do the anterior and long posterior ciliary arteries supply?
Iris and ciliary body
88
What is the venous drainage of the eye?
Vortex veins and central retinal veins
| Drain into cavernous sinus
89
Which extraocular muscles does the oculomotor cranial nerve III innervate?
Superior, medial, inferior rectus
Inferior oblique
Levator palpebrae superioris
90
Which extraocular muscles does the trochlear cranial nerve IV innervate?
Superior oblique
91
Which extraocular muscles does the abducent cranial nerve VI innervate?
Lateral rectus
92
Which nerve supplies sensation to eyelids, conjunctiva and cornea?
Trigeminal V1 - ophthalmic
93
Which nerve is involved with constriction of the pupil?
Parasympathetic fibres of oculomotor cranial nerve III
94
Which nerve is involved with dilation of the pupil?
Sympathetic fibres of trigeminal cranial nerve V1 - ophthalmic
95
What may an aneurysm in the posterior communicating artery cause?
Compression of CN III oculomotor (pupil constrictor and levator palpebrae superioris)
Dilated pupil
Ptosis
96
What does the score of 6/12 mean with snellen chart?
6 meters form chart
| Lowest line read is the lowest line that you should see at 12 meters
97
What snellen chart score is required for driving?
Minimum of 6/12
98
What isa LogMAR chart and how is it different from a snellen chart?
Log of minimum angle of resolution chart
More accurate than Snellen as each line has the same no of letters
Letter size and spacing varies logarithmically
99
What changes are observed in background diabetic retinopathy?
Blot and dot haemorrhages
Hard exudates
Microaneurysms
100
What changes are observed in pre-proliferative diabetic retinopathy?
Venous bleeding
Soft exudates/ Cotton wool spots
Intraretinal microvascular abnormalities (IRMA) - capillary walls loose their elasticity and dilate
101
What changes are observed in proliferative diabetic retinopathy?
Neovascularization - that tend to bleed
Pre-retinal haemorrhage and fibrosis
Vitreous haemorrhage
Traction retinal detachment
102
How is proliferative diabetic retinopathy treated?
Laser panretinal photocoagulation
(Seals/ destroys abnormal/ leaking vessels
Reduces ischaemic load)
Also vitrectomy, pharmacological vitreolysis, anti-angiogenic treatment
103
What are the 3 types of diabetic maculopathy?
Exudative
Oedematous
Ischaemic
104
What changes are observed in mild non-proliferative diabetic retinopathy?
Microaneurysms
105
What changes are observed in moderate non-proliferative diabetic retinopathy?
Cotton wool spots
Venous beading
Intraretinal microvascular abnormalities (IRMA) - capillary walls loose their elasticity and dilate
106
Which retinopathy signs indicate referral to secondary care?
Haemorrhages/ microaneurysms in 4 quadrants
Venous beading in 2+ quadrants
IRMA in 1+ quadrant
107
What changes are observed in diabetic macular oedema?
Retinal thickening
| Hard exudates
108
How is diabetic macular oedema treated?
```
Focal laser
Vascular endothelial factor antagonist
Corticosteroids
Vitrectomy
Aspirin, PKC inhibitor, fenofibrate (tricor)
```
109
What could be causing central vision to be affected and to become constantly blurry?
Oedema in or very close the macula - clinically significant macular edema (CSME)
110
What do hard and soft exudates represent?
HE - cholesterol deposits
| SE (cotton wool spots) - capillary infarcts
111
What is the word for pupil dilation?
Mydriasis
112
Tropicamide is used to dilate pupils for ophthalmoscopy. How does it work?
Muscarinic antagonist
Blocks parasympathetic stimulating
Preventing pupil constriction
113
Tropicamide eye drops may be harmful to who?
Dangerous to patients with narrow angle (between iris and cornea) glaucoma
As drops may increase intraocular pressure
These patients already have increased intraocular pressure as humor drainage is blocked by narrow angle
114
Tropicamide eye drops may cause cycloplegia, what is cycloplegia?
When the ciliary muscle relaxes causing paralysis of accommodation
115
What does cupping refer to in ophthalmology?
Cupping of optic disc, can be normal
Cup: disc ratio show diameter of disc occupied by cupping
Increase with age may indicate glaucoma
116
What is papilloedema?
Swelling of optic disc caused by increase in intracranial pressure
117
What is AV nipping and when is it most commonly seen?
Ateriovenous nipping
Small artery crosses over small vein, compressing the vein
Vein bulges on either side of compression
Seen in hypertension
118
Does the artery or vein appear thicker in ophthalmoscopy?
Retinal veins appear thicker
119
How does neovascularisation occur in the eye?
Existing blood vessels occluded
Lack of perfusion
Release of VEGF (vascular endothelial growth factor)
Cause new blood vessels to sprout
120
How could you tell which eye (L/R) you were looking at in a fundus picture?
Macula is temporal (lateral) to disc
Disc is nasal side
If disc in on R side then you're looking at the R eye
121
What should PaO2 be if breathing normal air?
>10kPa
122
What should PaO2 be if on oxygen?
About 10kPa less than % inspired concentration
123
What is the PaCO2 in respiratory acidosis (or respiratory compensation for metabolic alkalosis)?
PaCO2 > 6 kPa
124
What is the normal base excess?
+/- 2 mmol l-1
125
What is the HCO3- concentration in metabolic alkalosis (or renal compensation for respiratory acidosis)?
HCO3- > 26 mmol l-1
126
What is FiO2?
Fraction of inspired oxygen
127
What if a patient given high flow oxygen via a face-mask with FiO2 of 85% and has a PaO2 of 18.8kPa?
PaO2 is above the normal range (>10kPa)
However PaO2 would be expected to be around 75 kPa when breathing 85% oxygen
= significant impairment in oxygenation
128
What is tachypnea?
Abnormally rapid breathing
129
What's the difference between tachypnea/ hyperpnea and hyperventilation?
In tachypnea and hyperpnea, increased ventilation is appropriate for a metabolic acidotic state (also known as respiratory compensation)
Whereas in hyperventilation, increased ventilation is inappropriate for the metabolic state of blood plasma
130
What does hyperventilation cause?
Low CO2 - hypocapnia
131
What does impaired ventilation cause?
Reduced oxygen in blood - hypoxaemia
| Increased PaCO2
132
What does a negative base excess below -2 mean?
There's abnormally low HCO3- levels
Negative base excess
Metabolic acidosis
133
What does a positive base excess above 2 mean?
There's abnormally increased HCO3- levels
| Metabolic alkalosis
134
What information can be deduced from arterial blood gas analysis?
Patient's acid-base status and respiratory gas exchange
135
What is a nanomole?
1 billionth of a mole
| a mole is the molecular weight of a substance in grams
136
If a patient had a base excess of 8 mmol L-1, what would return their pH to normal?
8 mmol l-1 of strong acid would be required to return their pH to normal
137
If a patient had a base excess of -8 mmol L-1 (base deficit of 8 mmol L-1), what would return their pH to normal?
8 mmol l-1 of strong base would be required to normalise their pH
138
How can chronic hypokalaemia lead to metabolic alkalosis with respiratory compensation?
```
Body compensates by moving potassium from intracellular to extracellular in exchange for H+
pH increases (H+ out of blood) and CO2 is retained to try and compensate
```
139
What does ELISA stand for?
Enzyme-linked immunological assay
140
When do those on a two dose regime inject insulin?
Before breakfast
| Before evening meal
141
When do those on a three dose regime inject insulin?
Before breakfast
Before evening meal
Before bedtime
142
When do those on a multiple daily injection regime inject insulin?
With each meal and snack
| Before bedtime
143
Which insulin regimes allow flexibility with portion size and meal times?
Multiple daily injections
Insulin pump therapy
Three doses - allows flexibility with evening meal only
144
What is considered an alkalaemic pH and H+ concentration?
pH > 7.45
| H+ less than 35 nmol/L
145
What is the PaCO2 in respiratory alkalosis (or respiratory compensation for metabolic acidosis)?
PaCO2 less than 4.7 kPa
146
What is considered acidotic pH and H+ concentrations?
pH less than 7.35
| H+ > 45 nmol/L
147
What is the HCO3- concentration in metabolic acidosis (or renal compensation for respiratory alkalosis)?
HCO3- less than 22 mmol/L
148
What are the 5 steps to interpreting arterial blood gas?
1. How's the patient?
2. Oxygenation - uptake/ hypoxic
3. Acidosis/ alkalosis? - pH/ H+ conc.
4. Respiratory component - PaCO2
5. Metabolic component - base excess/ bicarbonate conc.
149
What are the 3 ketone bodies?
Acetoacetate
Beta-hydroxybutyrate
Acetone
150
In terms of ABG how can initially assessing the patient help direct you towards the problem?
Hyperventilation - decreases PaCO2 - respiratory acidosis
Drowsy/ COPD/ bronchospasm in asthma - impaired ventilation - increases PaCO2 - respiratory acidosis
DKA (ketones)/ MI (lactic acid) - metabolic acidosis
151
What is Conn's syndrome?
Excess aldosterone
| Increased bp from increased water reabsorption
152
What does aldosterone do?
Stimulate:
Secretion of K+ and H+ into urine
Reabsorption of Na+ and water into blood - increasing intravascular volume
