Hyperparathyroidism

Question 1

What is hyperparathyroidism?

Answer 1

Raised parathyroid hormone (PTH)

Question 2

What is function of PTH

Answer 2

PTH is released by parathyroid glands in response to low serum calcium levels in order to raise it, by:

* Increasing osteoclast activity to release Ca and PO4 into blood
* Increasing Ca and decreasing PO4 reabsorption from kidneys 
* Increases active vitamin D production

Question 3

What are causes of primary hyperparathyroidism

Answer 3

adenoma, hyperplasia of glands, carcinoma

Question 4

What are cause of secondary hyperparathyroidism

Answer 4

Caused by low vitamin D intake, CKD.

Question 5

What are causes of tertiary hyperparathyroidism

Answer 5

Prolonged secondary, glands act autonomously following hyperplastic/adenomatous change, and produce loads of PTH despite Ca levels. Seen in CKD.

Question 6

What is malignant hyperparathyroidism?

Answer 6

PTHrP secreted by some squamous cell lung cancers, breast, and RCC. PTH is low and Ca high.

Question 7

What are Sx of hyperparathyoidism?

Answer 7

Often asymptomatic, may be Sx of hypercalcaemia in primary e.g. pain, OP and fractures, fatigue, myalgia, renal stones, abdominal pain

Secondary: osteomalacia, rickets

MEN1

Question 8

What Ix in hyperparathyoidism?

Answer 8

PTH raised

Ca: high (1) or low (2).

PO4: low (1) or high (2)

Check vitamin D (may be cause)

Urine calcium: creatinine ratio (differentiate from FHH where usually <0.01)

Imaging: x-ray showing pepperpot skull.
DEXA to check for OP.

Question 9

What is Rx of hyperparathyoidism?

Answer 9

Fluids to prevent renal stones.

Observation if no end-organ damage or unfit for surgery

bisphosphonates
calcimimetics e.g. cinacalcet (reduce serum Ca but doesn’t prevent end organ damage)
parathyroidectomy

vitamin D

Question 10

What are indications for parathyroidectomy?

Answer 10

Calcium > 3.0 mmol/L; hypercalciuria; osteoporosis; age under 50 years; intractable symptoms; renal stones.

Question 11

What are complications of hyperparathyroidism?

Answer 11

End organ damage to bones (OP), kidneys (stones, CKD), and others e.g. pancreatitis, hypoparathyroidism

Question 12

What are complications of parathyroidectomy?

Answer 12

Mechanical
○ Vocal cord paresis
○ Haematoma causing tracheal compression

Metabolic
○ Transient hypocalcaemia (suppression of remaining glands)
○ May require oral calcium / vit D supplementation

Hungry bones: Sudden withdrawal of PTH leads to imbalance between bone formation and resorption – marked net increase in uptake of calcium, phosphate and magnesium by bone
Requires calcium and vitamin D supplementation