Vitamin D and primary hyperparathyroidism (PHPT).
Vitamin D deficiency and primary hyperparathyroidism (PHPT) are two common conditions, especially in postmenopausal women. Vitamin D deficiency is said to be even more frequent in PHPT patients than in the general population due to an accelerated conversion of 25-hydroxy vitamin D (25OHD) into calcitriol or 24-hydroxylated compounds. Although several studies have reported worsening of PHPT phenotype (larger tumours, higher parathyroid hormone [PTH] levels, more severe bone disease) when vitamin D deficiency coexists whereas vitamin D supplementation in PHPT patients with a serum calcium level less than 3 mmol/L has been shown to be safe (no increase in serum or urinary calcium) and to decrease serum PTH concentration, many physicians are afraid to give vitamin D to already hypercalcemic PHPT patients. It is possible that, in some patients, a persistent vitamin D deficiency induces, in the long-term, an autonomous secretion of PTH (i.e. tertiary hyperparathyroidism). The mechanism by which this could occur is unclear however. Finally, as many, otherwise normal, subjects with vitamin D insufficiency may have an increased serum PTH level we believe that those with vitamin D insufficiency should be excluded from a reference population for serum PTH levels. By doing that, we found that the upper normal limit for serum PTH was 25-30% lower than in the whole population.
Service d'explorations fonctionnelles, laboratoire d'explorations fonctionnelles, hôpital Necker-Enfants-Malades, 149, rue de Sèvres, 75015 Paris, France. jean-claude.souberbielle@nck.aphp.fr
Jean-Claude
JC
Souberbielle
Frank
F
Bienaimé
Etienne
E
Cavalier
Catherine
C
Cormier
D002986:Clinical Trials as Topic; D015897:Comorbidity; D000075202:Contraindications; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced / Q000188:drug therapy / Q000209:etiology; D006961:Hyperparathyroidism / Q000139:chemically induced; D049950:Hyperparathyroidism, Primary / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D007668:Kidney / Q000503:physiopathology; D008297:Male; D015663:Osteoporosis, Postmenopausal / Q000209:etiology / Q000517:prevention & control; D010281:Parathyroid Hormone / Q000097:blood* / Q000378:metabolism; D017698:Postmenopause; D017410:Practice Guidelines as Topic; D011933:Reagent Kits, Diagnostic; D012016:Reference Values; D014807:Vitamin D / Q000009:adverse effects / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000150:complications / Q000453:epidemiology*
D010281:Parathyroid Hormone; D011933:Reagent Kits, Diagnostic; D014807:Vitamin D