title: Vitamin D deficiency rickets mimicking pseudohypoparathyroidism.
abstract: Vitamin D deficiency rickets (VDDR) is a disorder biochemically characterized by elevated serum alkaline phosphatase (ALP) activity, normal or decreased serum calcium (Ca) and inorganic phosphate concentrations, secondary hyperparathyroidism and decreased serum 25-hydroxyvitamin D (25(OH)D) levels. In stage 1 VDDR, urinary amino acid and phosphate excretion are normal with minimal or no findings of rickets on radiographs. Pseudohypoparathyroidism (PHP) is an inherited disorder characterized by end-organ resistance to parathormone (PTH). VDDR occasionally resembles PHP type 2 in clinical presentation and biochemical features, creating difficulties in the differential diagnosis of these two entities. Here we report an infant diagnosed with VDDR. In addition to inadequate vitamin D intake, usage of antiepileptic drugs (AED) may have led to the worsening of the vitamin D deficiency. The patient presented with a history of febrile convulsions, for which he received phenobarbital treatment. The initial findings of hypocalcemia, hyperphosphatemia and normal tubular reabsorption of phosphate, mimicking PHP 2, responded well to vitamin D and oral Ca treatment with normalization of serum Ca, phosphorus (P), ALP and PTH levels.
authors.affiliation: Department of Pediatrics, Erciyes University Faculty of Medicine, Kayseri, Turkey. leylabakin@gmail.com
authors.forename: Leyla
authors.initials: L
authors.lastname: Akın
authors.forename: Selim
authors.initials: S
authors.lastname: Kurtoğlu
authors.forename: Aysel
authors.initials: A
authors.lastname: Yıldız
authors.forename: Mustafa Ali
authors.initials: MA
authors.lastname: Akın
authors.forename: Mustafa
authors.initials: M
authors.lastname: Kendirici
mesh_terms: D000927:Anticonvulsants / Q000009:adverse effects*; D002118:Calcium / Q000097:blood / Q000627:therapeutic use; D003937:Diagnosis, Differential; D006801:Humans; D007223:Infant; D008297:Male; D010634:Phenobarbital / Q000009:adverse effects*; D010710:Phosphates / Q000097:blood; D011547:Pseudohypoparathyroidism / Q000175:diagnosis*; D012279:Rickets / Q000175:diagnosis*; D012640:Seizures / Q000188:drug therapy; D014807:Vitamin D / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000139:chemically induced* / Q000175:diagnosis / Q000188:drug therapy
chemical_list: D000927:Anticonvulsants; D010710:Phosphates; D014807:Vitamin D; D002118:Calcium; D010634:Phenobarbital