Secondary Hyperparathyroidism in Patients With Ichthyosis Is Not Caused by Vitamin D Deficiency or Ingestion of Retinoids

Abstract

To the Editor.— We recently reported that five of 15 patients with various disorders of keratinization had secondary hyperparathyroidism. 1 We now confirm and extend those observations to a larger, totally separate group of patients. Patients and Methods.— Families with epidermolytic hyperkeratosis, lamellar ichthyosis, congenital nonbullous ichthyosiform erythroderma, ichthyosis vulgaris, and Darier's disease answered an advertisement to participate in studies on the genetic basis of their disease(s). Diagnoses were established by clinical findings, inheritance pattern, and skin biopsy specimens of at least one member of each family. Coded serum and plasma samples were immediately frozen and shipped to New Haven, Conn, for analysis of parathyroid hormone (PTH), creatinine, calcium, 25(OH) vitamin D, and 1,25 (OH) 2 vitamin D as previously described. 1 Results.— Samples from 65 patients were analyzed. The patients fell into two distinct groups: those with normal serum PTH values and those with PTH levels at least 1.8