Over-supplementation of vitamin D in two patients with primary hyperparathyroidism.
OBJECTIVE
To describe the biochemical effects of an over-supplementation of vitamin D3 in two patients with primary hyperparathyroidism (PHPT).


METHODS
Two patients (A and B) with PHPT took erroneously 2,400,000 U (300,000 U/day for 8 days) and 4,500,000 U (300,000 U/day for 15 days) of cholecalciferol, respectively. They were followed for 4 months and ionized calcium, creatinine, PTH, 25 hydroxy-vitamin D, 1,25(OH)₂D and urinary calcium/creatinine levels were measured. Finally, the patients were operated on and a parathyroid adenoma was removed in both.


RESULTS
One week after the last dose of vitamin D, serum ionized calcium (iCa) rose from 1.35 to 1.41 mMol/L (n.r. 1.14-1.31) for patient A, and from 1.43 to 1.62 for patient B, while fasting urinary Calcium/Creatinine (uCa/Cr) augmented from 0.31 to 0.50 mg/mg, and from 0.32 to 0.55, respectively. During the follow-up, the average levels of iCa were 1.37 ± 0.03 and 1.48 ± 0.07 mMol/L, while those of uCa/Cr were 0.29 ± 0.13 and 0.32 ± 0.13, both iCa and uCa/Cr levels returning to baseline values within 4 months.


CONCLUSIONS
The unintentional over-supplementation of vitamin D in the two PHPT patients caused a moderate and temporary increase of hypercalcemia and hypercalciuria and was not associated with clinical signs of toxicity.
Unit of Endocrinology, "Casa Sollievo della Sofferenza" Hospital, IRCCS, San Giovanni Rotondo (FG), Italy.
Claudia
C
Battista
Unit of Endocrinology, "Casa Sollievo della Sofferenza" Hospital, IRCCS, San Giovanni Rotondo (FG), Italy.
Raffaella
R
Viti
Department of Clinical Sciences, University of Roma "Sapienza", Italy.
Salvatore
S
Minisola
Unit of Endocrinology, Department of Medical Sciences, Fondazione Policlinico IRCCS, University of Milan, Italy.
Iacopo
I
Chiodini
Unit of Nuclear Medicine, "Casa Sollievo della Sofferenza" Hospital, IRCCS, San Giovanni Rotondo (FG), Italy.
Vincenzo
V
Frusciante
Unit of Endocrinology, "Casa Sollievo della Sofferenza" Hospital, IRCCS, San Giovanni Rotondo (FG), Italy.
Alfredo
A
Scillitani
Unit of Internal Medicine, "Casa Sollievo della Sofferenza" Hospital, IRCCS, San Giovanni Rotondo (FG), Italy.
Vincenzo
V
Carnevale
D000236:Adenoma / Q000601:surgery; D002118:Calcium / Q000097:blood / Q000652:urine; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006706:Homeostasis; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000188:drug therapy* / Q000378:metabolism; D008875:Middle Aged; D010282:Parathyroid Neoplasms / Q000601:surgery; D016105:Parathyroidectomy; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage* / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000188:drug therapy* / Q000378:metabolism
D014807:Vitamin D; D002118:Calcium