Which of the following is a cause of secondary hyperparathyroidism?
|D||All of the above|
All of the above
Hyperparathyroidism (Ref: Hari-18th ed., Pg-3110)
1). Primary hyperparathyroidism
↑Ca, ↓PO4, ↑PTH
a. The most common cause of primary hyperparathyroidism is parathyroid solitary adenoma.
b. “A single solitary abnormal gland is the cause of approximately 80% of patients”
c. The abnormality of the gland is usually a benign neoplasm or adenoma and rarely a parathyroid carcinoma.
a. Adenomas are most often located in the inferior parathyroid glandq.
b. Chief cells are predominant in both hyperplasia and adenoma.
2). Secondary hyperparathyroidism: Ca2+↓, PTH↑ (MCQ) ↑ PO4
Causes Low vitamin D intake, chronic renal failure, Rickets, osteomalacia, malabsorption (FAQ)
The "trade-off hypothesis" for Ca2+/PO42–homeostasis with progressively declining renal function.
(Ref. Hari -18th ed. Pg-2289)
In CRF, serum calcium level decreases and serum phosphate level increases.
3). Tertiary hyperparathyroidism: Ca2+↑, PTH↑ (FAQ)↓ PO4
Occurs after prolonged secondary hyperparathyroidism, causing glands to act autonomously having undergone hyperplastic or adenomatous change.
This causes Ca2+ from secretion of PTH unlimited by feedback control. Seen in chronic renal failure.
4). Malignant hyperparathyroidism
Causes: Parathyroid-related protein (PTHrp) is produced by some squamous cell lung cancers, breast and renal cell carcinomas. (FAQ)
Extra Edge: Hypercalcemia in malignancy occur due to increase level of PTHrp. In this PTH level are not raised (AIIMS Nov 09).