OK, today we are going to discuss an important topic in endocrinology in MRCP, we are going to talk about hyperparathyroidism.
Hyperparathyroidism just means high levels of circulating parathyroid hormone. You must remember that there are three types of hyperparathyroidism, primary, secondary and tertiary.
1) Primary hyperparathyroidism
It is simple, there is no reason ( such as low Calcium level) for the raised parathyroid hormone. It is usually due to problems occurring to the parathyroid gland itself. Causes are adenoma, parathyroid hyperplasia or carcinoma.
2) Secondary hyperparathyroidism
Parathyroid gland is stimulated to secrete more parathyroid hormone due to some underlying reason such as low calcium because of renal failure, Vitamin D deficiency.
3) Tertiary hyperparathyroidism
After prolonged stimulation, the parathyroid gland becomes autonomous and secrets parathyroid hormone without any feedback mechanism
I hope to discuss more about primary hyperparathyroidism today because clinically, we see secondary and tertiary hyperparathyroidism mainly in renal failure patients.Therefore, they are not so important in your MRCP Part 1 and 2!
Presentation of Hyperparathyroidism
As you might still remember as a medical student, parathyroid hormone's main function is to mobilize calcium from bone ( therefore leading to hypercalcemia) and increase urinary phosphate excretion, therefore patients with primary hyperparathyroidism usually present with symptoms due to hypercalcemia.
Remember this old mnemonic:' bone,stones, abdominal groans and psychic moans'!
Other presentations include dehydration ( due to increased diuresis, the reason? Check your book now!), thirst, confusion and myopathy.
Clinical Signs
Not thing much to see and examine unless you get a patient with a very big adenoma or carcinoma. However, always look for associated endocrine neoplasia associated with hyperparathyroidism in MEN ( Multiple Endocrine Neoplasia) I and II such as hypertension ( due to phaeochromocytoma), features of acromegaly due to pituitary adenoma.
Investigations
Raised calcium with ALP
Urine calcium excretion is raised
Xray may show osteitis fibrosa cystica,pepper-pot skull and subperiosteal resorption
Plasma PTH- inapproriately raised! (of course!)
Treatment
Removal of the gland
Indications for operation ( American NIH consensus)
1) markedly elevated calcium (>3mmol)
2) impaired renal function
3) renal stones
4) nephrocalcinosis
5) reduced BMD
6) substantially elevated urinary calcium excretion (>10mmol/24h)
Tips for MRCP
1) remember to suspect MEN every time you diagnose primary hyperparathyroidism
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