Osteomalacia is an uncommon cause of muscle weakness. Our objectives were to describe features of myopathy associated with Vitamin D deficiency and examine the contributing factors leading to osteomalacic myopathy in our region.

Patients identified retrospectively for the six year period ending in December 2006 with the diagnosis of osteomalacia and/or Vitamin D deficiency associated proximal muscle weakness were included. They were followed in three major centers in western Saudi Arabia. Clinical, biochemical, radiological, and electrophysiological findings were collected before and after Vitamin D treatment by chart review.

Forty seven female patients aged 13-46 years (mean 23.5, SD 4.5) were included. All were veiled and covered heavily when outside the house for social and cultural reasons. Only eight (17%) had adequate varied diet with daily milk ingestion. All patients presented with progressive proximal muscle weakness lasting 6-24 months (mean 14) prior to our evaluation. The weakness was severe in six (13%) patients leading to wheel chair bound states. Associated musculoskeletal pain involving the back, hips, or lower limbs was common (66%). Osteomalcia was the referral diagnosis in only 11 patients and the remaining 36 (77%) patients were misdiagnosed. All patients had metabolic and radiological profiles suggestive of osteomalacia. Remarkable recovery was documented in all patients following oral cholecalciferol and calcium supplementation.

Vitamin D deficiency is an important treatable cause of osteomalacic myopathy in Saudi Arabia. The diagnosis is frequently delayed or missed. Screening for Vitamin D deficiency in patients with acquired myopathy is needed to identify this treatable disorder.