Abstract
As the detection of subclinical hypoparathyroidism in transfused thalassemic patients is hampered by assay insensitivity at low PTH levels, we used a provocation test as a dynamic measure of PT reserve. PTH response was assessed by using urinary cyclic AMP (cAMP) as a function of response. cAMP excretion correlates well with PTH activity, particularly when combined with plasma cAMP to calculate nephrogenous cAMP excretion.
Eight patients aged 9-26 with thalassemia major and iron overload (ferritin 2-6 μg/ml vs normal <0.15),all with normal baseline serum calcium and phosphorus, and 4 young adult controls received 50 mg/kg disodium EDTA IV over 3 hours. Ionized calcium fell by 0.64 ± .33 mg% (controls 0.87 ± .33). Urinary cAMP rose by 1-5.2 nmol/100 ml glomerular filtrate (GF); control 1.2-5.1. In 4 patients nephrogenous cAMP rose 1.3-2.8 fold (controls 2.0-10.2 fold). The oldest patient showed the lowest rise in urinary cAMP (1.0 nmol/100 ml GF) and in nephrogenous cAMP (1.3 fold rise).
We conclude that the response of the nephrogenous component of urinary cAMP to PT provocation with EDTA is a reliable, generally applicable test of PT reserve. The finding of well preserved PT function in at least 7 of our 8 patients is consistent with the clinical observation that overt hypoparathyroidism is a late and uncommon complication of thalassemia major. (Supported by Grant RR-125, GCRC Branch, NIH.)
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gertner, J., Broadus, A., Grey, M. et al. 854 STIMULATED NEPHROGENOUS CYCLIC AMP AS A PARATHYROID (PT) FUNCTION TEST IN THALASSEMIA MAJOR. Pediatr Res 12 (Suppl 4), 506 (1978). https://doi.org/10.1203/00006450-197804001-00859
Issue Date:
DOI: https://doi.org/10.1203/00006450-197804001-00859