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Circulating parathyroid hormone activity: familial hypocalciuric hypercalcemia versus typical primary
The Journal of Clinical Endocrinology and Metabolism
|December 1, 1978
Summary
Familial hypocalciuric hypercalcemia (FHH) and primary hyperparathyroidism (1HPT) show distinct parathyroid hormone (PTH) activity. FHH exhibits lower circulating PTH activity and altered renal phosphate transport compared to 1HPT.
Area of Science:
- Endocrinology
- Nephrology
- Genetics
Background:
- Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant disorder characterized by hypercalcemia without hypercalciuria.
- Primary hyperparathyroidism (1HPT) is a common endocrine disorder often presenting with hypercalcemia.
Purpose of the Study:
- To compare circulating parathyroid hormone (PTH) activity indices between FHH and 1HPT patients.
- To investigate the differences in renal handling of calcium and phosphate in FHH versus 1HPT.
Main Methods:
- Comparison of plasma PTH concentration, urinary cAMP excretion per 100 ml glomerular filtrate (U cAMP/GF), and renal tubular maximum of phosphate transport corrected for glomerular filtration rate (TMP/GFR) between FHH and 1HPT groups.
- Statistical analysis including adjustments for serum calcium concentration, age, and creatinine clearance.
Main Results:
- 1HPT patients showed significantly higher PTH, UcAMP/GF, and lower TMP/GFR compared to normal individuals.
- FHH patients exhibited significantly lower PTH and UcAMP/GF, but higher TMP/GFR compared to 1HPT patients.
- TMP/GFR remained significantly different between FHH and 1HPT after adjusting for multiple covariates, while UcAMP/GF did not.
Conclusions:
- Higher serum PTH concentrations do not explain the reduced renal calcium and magnesium clearance in FHH.
- FHH patients demonstrate indices suggestive of lower circulating PTH activity than 1HPT patients.
- Parathyroid glands may contribute to mineral homeostasis abnormalities in some FHH cases.