128; GEN Endocrine Flashcards
What cells secrete PTH?
Chief Cells of the parathyroid glands
What is the function of PTH?
- Increase tubular reabsorption of Ca
- VitD production
- Osteoclast mediated bone resorption
What is the most common cause of Hypercalcaemia?
- Primary hyperparathyroidism
- Malignancy
Less common
Milk-alkali syndrome
Diet
Thiazide diuretics
Sarcoid
Familial Benign Hypocalciuric Hypercalcaemia
What are the biological effects of PTH excess in Serum and urine tests?
Serum
- ↑Calcium
- ↑ PTH
- ↑Alkaline phosphatase
- ↑Chloride
- ↓Bicarbonate
- ↓Phosphorus
Urine
- ↑Calcium
- ↑Phosphorus
- ↑cAMP
WHat are the causes of primary Hyperparathyroidism?
Parathyroid
- Adenoma
- Carcinoma
- Hyperplasia
What are the causes of secondary hyperparathyroidism?
- Hypocalcaemia
What are the causes of tertiary Hyperparathyroidism?
Autonomous secretion of PTH following long-term hypocalcaemia
(Autonomous- not sensitive to Ca levels any more although they may be raised)
What would would a symptomatic Pt with Primary hyperparathyroidism present with?
Stones
- Kidney stones, nephrocalcinosis
Groans
- Bone pain, fractures, proximal myopathy
Thrones
- Polyuria, Constipation, N&V
Psychiatric Overtones
- Depression, confusion, tiredness
Cardiac
- Bradycardia, Heart block
What is the epidemiology of primary hyperparathyroidism?
Men >50
Female post-menopausal
What are the familial causes of Hyperparathyroidism?
Multiple endocrine nepolasia (MEN) 1
MEN 2a
Familial hyperparathyroidism
Familial hyopcalciuric hypercalcaemia
What investigations would be done for hyperparathyroidism?
Serum
- Calcium
- Phosphate
- U&E
- PTH
- VitD
Urine
- 24H urinary calcium
Imaging
- Chest Xray
- Bone density
- US kidneys
What is the treatment for Hyperparathyroidism?
Conservative
- Hydration, avoid diuretics, diet
Surgical
- Adenoma; unilateral removal of PTHyroids
- Hyperplasia; total PTHyroidectomy, forearm transplantation, Thymus removal
- Carcinoma; Removal and thymectomy
What are the most common malignancies associated with hypercalcaemia?
Lung 35%
Breast 25%
Blood (myeloma, lymphoma) 14%
Head & neck 6%…
What is the mechanism behind Malignant Hypercalcaemia?
**Increased osteoclast bone resorption **
- Tumour secrete osteoclast stimulating factors:
- cytokines; interleukins, chemokines
- PTH-related peptide from squ. cell cancers and breast cancer
- Ectopic PTH production (rare)
What are the signs and symptoms of severe hypercalcaemia?
Serum Calcium > 3.5mmol/l
Reduced GFR & impaired renal calcium clearance
Impaired renl tubular reabsorption
Extracellular volume depletion
Elevated PTHrP levels
