Description
Parathyroid hormone is made by four tiny parathyroid glands in your neck. These glands control calcium levels in your blood. When calcium levels are too low, the glands release PTH to bring the calcium levels back up into a normal range. When your calcium levels rise, the glands stop releasing PTH.Measuring PTH can help explain the reason for abnormal calcium levels.
Diagnosis and differential diagnosis of hypercalcemia. Diagnosis of primary, secondary, and tertiary hyperparathyroidism. Diagnosis of hypoparathyroidism. Monitoring end-stage renal failure patients for possible renal osteodystrophy.
Intact PTH is a biologically active hormone produced by parathyroid hormones and secreted into systemic circulation.Intact PTH assays measures not only PTH (1-84) but other fragments including PTH (7-84) which may accumulate in patients with renal insufficiency.Decreased calcium levels stimulate PTH release. Secreted PTH causes rapid increase in renal tubular reabsorption of calcium and decrease in phosphorus reabsorption. PTH also functions by enhancing mobilization of calcium from bone and increasing renal synthesis of 1,25-dihydroxy vitamin D, which, in turn, increases intestinal calcium absorption. In rare inherited syndromes of parathyroid hormone resistance or unresponsiveness and in renal failure, PTH release may not increase serum calcium levels.
Parathyroid hormone (PTH) values should be interpreted in conjunction with serum calcium and phosphorus levels, and the overall clinical presentation and history of the patient.
An elevated PTH value with normal serum calcium are not always necessarily indicative of primary hyperparathyroidism. It is possible that the elevation in PTH is due to secondary causes, the most likely cause is due vitamin D deficiency.So if calcium is low and intact PTH is normal/low then it means that PTH not responding correctly possibility of hypoparathyroidism.And if calcium is high with intact PTH low it can be interpreted as PTH responding correctly so run other tests to check for non-parathyroid –related reasons for high calcium.
