Alfacalcidol

Pseudohypoparathyroidism (PHP) is a group of disorders characterized by end-organ resistance to parathyroid hormone (PTH), resulting in high serum PTH, low calcium, and high phosphate levels. Among its 5 subtypes, PHP type 1a is the most common and leads to hereditary osteodystrophy, marked by short stature, short metacarpals, and electrolyte abnormalities such as hyperphosphatemia and hypocalcemia, which can cause tetany and seizures. Rarely, PHP patients can experience pathological fractures of long bones. This report discusses a 22-year-old female with PHP who presented with myoclonic seizures and bilateral hip fractures. Initial symptoms included fits, flank pain, and later, leg weakness. Diagnosis was based on clinical history, elevated serum PTH, low calcium, high phosphate, bilateral cataracts, hypothyroidism, basal ganglia calcification, and family history. Treatment began with IV calcium, followed by alfacalcidol, oral calcium, and antibiotics, leading to symptom remission. Hip fractures were managed with a POP cast and later closed reduction. The patient was discharged with calcium and 1,25 dihydroxy Vitamin D supplementation and scheduled for regular follow-up.

Patients with severe motor and intellectual disabilities (SMID) often experience insufficient physical activity, leading to osteoporosis. The active form of vitamin D is commonly prescribed for the prevention or treatment of osteoporosis. We observed four cases of kidney injury believed to be associated with the administration of 1α-OH vitamin D (alfacalcidol) preparations. This study employed a case series design to investigate change in kidney function in SMID patients following administration or discontinuation of alfacalcidol. We retrospectively analyzed data of 23 SMID patients (sex: 10 males, 13 females; age range: 27 to 74 y), and assessed kidney function, serum calcium, and albumin levels. Data was grouped into A: 16 cases collected both before starting alfacalcidol administration and during alfacalcidol administration; and into B: 11 cases collected during alfacalcidol administration and after discontinuation of alfacalcidol administration. Of the 23 patients, four were assigned into both group A and group B. Of the 16 cases in group A, six showed ≥30% decreased kidney function. Of the 11 cases in group B, the median values of modified Cr-eGFR were 43.0 and 65.1 mL/min/1.73 m², respectively (p=0.008), indicating a significant improvement in kidney function. It is essential for practitioners to understand that osteoporosis may ordinarily occur in SMID patients due to reduced bone stimulation. Thus caution must be exercised when administering active vitamin D preparations to this population, as they carry a risk of kidney organ damage despite having no direct effect on bone health.