ENDOCRINOLOGY Flashcards
What does PTH do?
Increases serum calcium
Increases osteoclast activity to increase bone turnover releasing calcium and phosphaye
Increasesvitamin D3 production
Increases uptake of calcium in the kidneys
What are the causes of Primary Hyperparathyroidism?
Cancer of the parathyroid gland
80% Solitary Adenoma
(multifocal disease, hyperplasia, multiple adenoma, parathyroid carcinoma)
What are the clinical features of Primary Hyperparathyroidism?
- Elderly females with unquenchable thirst with inappropriately normal or raised parathyroid hormone*
Signs of hypercalcaemia
HTN
Raised ALP
How is Primary Hyperparathyroidism managed?
Fluids prevents stones
Total parathyroidectomy (remove the parathyroid glands) if:
- High blood calcium: Serum Calcium >1mg/dL above noral
- High urine calcium: Hypercalciuria >400 mg/day
- Life threatiening hypercalcaemia
- Nephrolithiasis
- > 50 y/o
- Neuromuscualr symptoms
- Reduction in bone mineral density
Calcimimetic agents: cinacalcet if not suitable for surgery
What causes Secondary Hyperparathyroidism?
Parathyroid gland HYPERPLASIA due to LOW CALCIUM due to CKD
What are the clinical features of Secondary Hyperparathyroidism?
Few symptoms
Eventually bone disease
Soft tissue calcification
How is Secondary Hyperparathyroidism managed?
Manage medically, indications for parathyroidectomy:
- Bone pain
- Persistent pruritis
- Soft tissue calcification
What are the causes of Tertiary Hyperparathyroidism?
Ongoing hyperplasia of all 4 glands after CKD is corrected
What are the clinical features of Tertiary Hyperparathyroidism?
Metastatic calcification Bone pain and/or fractures Nephrolithiasis Pancreatitis Raised ALP
How is Tertiary Hyperthyroidism managed?
Only treat after 12 month persistance because it usually resolves
Remove culprit gland or all
What are the causes of Malignant Hyperparathyroidism?
PTH related-peptide produced by some Squamous cell Lung cancers, Breast cancers and renal cell carcinomas
What are the hormone levels in the hypeparathyroidisms?
1’ Raised: PTH Calcium
Low: Phosphate
2’ Raised: PTH Phosphate
Lowered: Calcium Vitamin D
3’ Raised: PTH Calcium
Lowered: Phosphate Vitmain D
Malignant: Raised: Calcium
Lowered: PTH (because PTHrp is raised)
What are the causes of primary hypoparathyroidism?
Gland failure
- AI
- Di geoge syndrome
- Thyroid surgery
What are the features of primary hypoparathyroidism?
Hypocalcaemia
High phosphate
How is primary hypoparathyroidism manged?
Calcium supplements
Calcitriol
Synthetic pTH
What are the causes of secondary hypoparathyroidism?
Radiaiton
Surgery
Hypomagensia
What is pseudo hypoparathyroidism?
Target cells are insensitive to PTH (due to a G protein abnormality) so PTH is actually high (calcium is low)
- Low IQ
- Short stature
- Short 4th abd 5th metacarpals
- Calcified basal ganglia
What is pseudopsuedo hypoparathyroidism?
Same features but normal biochemistry
What do the zones of the Adrenal Cortex produce?
Zona Glomerulosa- Mineralcorticoids
Zona Fasiculata- Glucocorticoids
Zona Reticularis- Sex steroids
What is Cushing’s syndrome?
CLINICAL STATE reduced by chronic EXCESS of GLUCOCORTICOIDS, loss of normal feedback mechanism and loss of CORTISOL secretion circadian rhythm
What are the causes of Cushing’s syndrome?
ACTH independent:
the adrenal gland is making too much cortisol and the ACTH is low. ADRENAL TUMOUR or bilateral adrenal hyperplasia
ACTH dependent:
- Cushing’s disease: Bilateral adrenal hyperplasia from PITUITARY ADENOMA secreting ACTH
- ECTOPIC ACTH production e.g. Small cell lung cancer
What are the symptoms of Cushing’s syndrome?
Acne
Mood changes (depressed, lethargic irritable, psychosis)
Hirsutism
Increased weight
Acanthiosis Nigricans (brown velvety skin discoloration e.g. in axilla)
Erectile dysfunction/Irregular menses
Recurrent achilles tendon rupture
What are the signs of Cushing’s syndrome?
Infections Moon face Buffalo hump Central obesity Purple striae Poor healing Skin and muscle hypertrophy Bruising Osteoporosis
What are the tests for Cushing’s syndrome?
1st line:
- overnight DEXAMETHASONE SUPRESSION TEST (should suppress to <50nmmol/L
or
- 24 hour urinary free cortisol
2nd line:
48 hour dexamethasone suppression
High-dose DMST differentiates between pituitary and non-pituitary causes
What is Primary Adrenal Insufficiency?
Autoimmune (Addison’s), Infective (TB, HIV, meningiococcal septicaemia), Metastases and Anti-phospholipid syndrome cause significant BILATERAL damage to the adrenal glands. This IMPAIRS ALL 3 LAYERS of the cortex and loss of negative fb causes the PITUITARY INCREASES ACTH PRODUCTION
What are the signs and symptoms of reduced function of the Zona Glomerulosa?
Reduced production of mineralcorticoids so reduced serum aldosterone.
Increased sodium lost -> HYPONATRAEMIA -> water lost -> HoTN (postural)-craving for salt
K+ retained -> HYPERKALAEMIA
H+ retained -> METABOLIC ACIDOSIS
What are the signs and symptoms of reduced function of the Zona Fasiculata?
Reduced production of glucocorticoids so reduced serum cortisol
Reduced ability to mobilise glucose into blood stream causes HYPOGLYCAEMIA
Increased Vasodilation (cortisol is a vasoconstrictor) HOTN (POSTURAL)
SIADH (cortisol usually inhibits) HYPONATRAEMIA
MALAISE FATIGUE ANOREXIA WEIGHT LOSS WEAKNESS ABDOMINAL PAIN JOINT AND MUSCLE PAIN N&V MOOD CHANGES: depression and psychosis
What are the signs and symptoms of reduced function of the Zona Fasiculata?
Reduced testosterone in women (because adrenals are only source)
Reduced axillary and pubic hair, reduced libido
How is Primary Adrenal Insufficiency tested for?
Raised ACTH from pituitary due to lack of negative feedback from cortisol.
Short SYNACTHEN test: measure cortisol 30 min before and after giving 250ug IM of synacthen
9am cortsol <500mmol/L
Serum aldosterone levels
Na+, K+, BM, pH
How is Primary Adrenal Insufficiency managed?
Give HYDROCORTISONE
20-30mg/day in 2-3 divided doses with the majority in the morning
Avoid late in the day-can cause insomnia
Don’t stop
Double the dose if infection or increased stress
What is Acromegaly?
Excess of growth hormone
What are the causes of Acromegaly?
95% due to PITUITARY ADENOMA
<5% due to ectopic GHRH or GH production by other tumours
What are the features of Acromegaly?
Enlarged features, organs and
- Headaches
- Supraorbital bulging
- Vision defects
- Enlarged lips, tongue and nose: coarse features
- Jaw and dental changes
- Thyroid hypertrophy
- Voice changes
- Skin tags
- Galactorrhoea due to prolactin increase
- Cardiomegaly
- Hepatospleonmegaly
- HTN
- Carpal tunnel and enlarged hand breadth and feet
- Bowel polyps
- Nephromegaly
- Enlarged colon
- Acanthinosis Nigricans
- Osteoarthritis
What are the complications of Acromegaly?
HTN
DMT2
Cardiomyopathy
Colorectal cancer
How is Acromegaly tested for?
GH is not diagnostic
- OGTT with serial GH measurements, hyperglycaemia usually suppresses
- 25% have impaired glucose tolerence
- IGF-1 will be high
- MRI will show a pituitary tumour
How is Acromegaly managed?
Trans sphenoidal surgery to remove pituitary tumour
Somatostatin analouge inhibits GH
External irradiotion
Dopamine agonists used for raised prolactin
What is Metabolic Syndrome?
3 or more of:
- High waist circumference
- BMI >30 (central obesity)
- Raised trigylcerides
- Low HDL
- HTN
- Raised fasting blood glucose
individuals have insulin resistance (in muscle, liver and adipose) resulting in high levels of circulating insulin and C-Peptide levels
What is a phaeochromocytoma?
Neuroendocrine tumour of cromaffin cells in medulla of the adrenal glands that secretes high amounts of CATECHOLAMINES (mostly Noradrenaline and some Adrenaline)
How do Phaeochromocytomas present?
Sympathetic nervous system hyperactivity
- Skin sensations
- Riased H.R and Palpitations
- Raised BP
- Anxiety
- Diaphoresis (sweating)
- Headaches
- Pallor
- Weight loss
How are Phaeochromocytomas managed?
Measure catecholamines and metanephrines in blood
or urine
Give alpha adrenoceptor blocker (e.g. phenoxybenzamine) or SAA Antagoinst to preduce risk of hypertension during surgery
Salt load due to volume depletion
NEVER USE NON-SELECTIVE B BLOCKERS
Syrgically resect
What is the inheritence pattern of Multiple Endocrine Neoplasias?
A.D
What is MEN-I?
3 Ps
Parathyroid: hyperplasia -> hyperparathyroid
Pituitary tumours e.g. Prolactinoma
Pancreatic tumours e.g insulinoma/glucagonoma
+ adrenal
+ thyroid
MEN-I gene
What is MEN-IIa?
2 Ps
Medullary THYROID CA
Paraythyroid
Pheochromocytoma
RET Oncogene
What is MEN-IIb?
1 P
Medullary THYROID CA
Pheochromocytoma
+ marfanoid
+neuromas-thickening of nerve tissue in parts of body
RET Oncogene
What is Diabetes Mellitus?
Chronic hyperglycaemia due to reduced endogenous insulin or reduced effectiveness of insulin