Original Article

Under-recognized Hypoparathyroidism in Thalassemia

10.4274/jcrpe.0020

  • Hataitip Tangngam
  • Pat Mahachoklertwattana
  • Preamrudee Poomthavorn
  • Ampaiwan Chuansumrit
  • Nongnuch Sirachainan
  • La-or Chailurkit
  • Patcharin Khlairit

J Clin Res Pediatr Endocrinol 0;0(0):0-0 [e-Pub] PMID: 29726397

Objective:

Symptomatic hypoparathyroidism [symptomatic hypocalcemia without elevated serum parathyroid hormone (PTH)] in patients with thalassemia is relatively rare. Asymptomatic mild hypocalcemia without elevated PTH which is considered hypoparathyroidism may be more common but under-recognized.

Methods:

Sixty-six transfusion-dependent thalassemic patients, and 28 healthy controls were enrolled. Serum calcium (Ca), phosphate (P), creatinine (Cr), albumin, intact PTH, 25-hydroxyvitamin D (25-OHD), plasma intact fibroblast growth factor-23 (FGF-23), urine Ca, P and Cr were measured. Tubular reabsorption of phosphate was calculated.

Results:

Thalassemic patients had significantly lower median serum Ca levels than the controls [8.7 (7.8-9.7) vs. 9.6 (8.7-10.1) mg/dL]. Hypoparathyroidism was found in 25 of 66 (38%) patients. Symptomatic hypoparathyroidism was not found. Thalassemic patients also had significantly lower median plasma FGF-23 levels than the controls [35.7 (2.1-242.8) vs. 53.2 (13.3-218.6) pg/mL]. In patients with hypoparathyroidism, median plasma FGF-23 level was significantly lower than that of patients with normoparathyroidism [34.8 (2.1-120.0) vs. 43.1 (3.2-242.8) pg/mL]. However, serum P, Cr, intact PTH and 25-OHD levels were not different.

Conclusion:

Hypoparathyroidism was not uncommon in patients with transfusion-dependent thalassemia treated with suboptimal iron chelation. Plasma intact FGF-23 level in patients with hypoparathyroidism was lower than that of patients with normoparathyroidism.

Keywords: thalassemia,,hypoparathyroidism,,hypocalcemia,,iron overload,FGF-23