-
Views
-
Cite
Cite
A. M. PARFITT, Study of Parathyroid Function in Man by EDTA Infusion, The Journal of Clinical Endocrinology & Metabolism, Volume 29, Issue 4, 1 April 1969, Pages 569–580, https://doi.org/10.1210/jcem-29-4-569
Close - Share Icon Share
Abstract
The response to a 2-hr infusion of Na3 EDTA was studied in 2 normals, 4 patients with pseudohypoparathyroidism and 15 patients who had undergone neck surgery, 11 with subsequent temporary hypocalcemia and 4 without. To establish non-arbitrary criteria of interpretation, these 21 cases and 129 others reported, were divided into 3 groups according to their status before the test: i) 64 normals, ii) 57 without prior evidence of parathyroid dysfunction other than treatment for hyperthyroidism, and iii) 29 with prior evidence of parathyroid dysfunction. The mean values of unchelated plasma calcium corrected to a preinfusion level of 10.0 mg/100 ml showed significant (p<0.001) differences between groups i and ii at 10 hr (C10) and between groups ii and iii at 22 hr (C22) after the end of the infusion (Time 0). Based on these results, 3 grades of response were defined, according to which the 21 cases in the present study were reclassified: grade 0 (normal)—C22 and C10 both ≥9.5 mg/100 ml (5/21 cases), grade 1—C22≥9.5 mg/100 ml >C10 (10/21 cases), and grade 2—C22 and C10 both <9.5 mg/100 ml (6/21 cases). The different rates of recovery in these 3 grades did not depend on differences in plasma phosphate or magnesium before or during the test or on intestinal absorption or tubular reabsorption of calcium; they reflect degrees of parathyroid insufficiency rather than degrees of adaptation to the aparathyroid state. Comparison of the results with predictions from a 3-compartment kinetic model of the exchangeable calcium pool suggests that mobilization of calcium from the non-exchangeable pool in bone normally begins at 2 hr and is maximal and almost complete at 10 hr; in subjects with a grade 1 response this process is delayed for 4 hr and prolonged by 12 hr, and in those with a grade 2 response it is absent, partial recovery resulting purely from passive rearrangement of the calcium remaining in the rapidly exchangeable pool.
