- excessive PTH secreted by parathyroid glads in response to hypocalcemia.
- Seen in chronic renal failure (most common cause of secondary HPT)
- Bone and joint pain are common
- Parathyroid hypertrophy
- no role for parathyroid surgery
- Vitamin D deficiency can cause secondary HPT
Normal calcium level with elevated PTH
Normal calcium blood levels with an elevated PTH might be due to vitamin D levels. Low vitamin D levels lead to elevated PTH levels to help maintain normal calcium blood levels.
Chronic Renal Failure
- Failing kidneys fail to convert enough vitamin D to its active form
- Does not adequately excrete phosphate into the urine
- Insoluble calcium phosphate forms in the body which removes calcium from the circulation – thus hypocalcemia and thus increases parathyroid hormone in an attempt to increase serum calcium levels
Other causes besides renal failure
- Malabsorption dependent bariatric surgery
- malabsorption due to chronic pancreatitis, small bowel disease
What is tertiary hyperparathyroidism?
Tertiary hyperparathyroidism occurs when the correction of the underlying cause will not stop excess PTH secretion
Vitamin D and Calcium?
The body needs vitamin D to absorb calcium from our diet.
What is primary hyperparathyroidism?
- Increased PTH secretion and raised serum calcium levels
- 85% caused by parathyroid adenoma (usually only one gland affected)
- 10% caused by chief cell hyperplasia
What is hungry bone syndrome?
- Severe Hypocalcemia seen after surgical correction of HPT
- Chronically deprived bone aggressively absorbs calcium