Vitamin D deficiency and rickets are more common in non-western immigrants and refugees than in the native population. Severe vitamin D deficiency (serum 25-hydroxyvitamin D < 25 nmol/l) may occur in up to 50% of children and adults of non-western origin. They are not used to sunshine exposure due to the often excessive sunshine in the country of origin. They usually have a more pigmented skin. Non-western immigrants and refugees often wear skin-covering clothes due to religious or cultural tradition. The food contains little vitamin D with the exception of fatty fish. In addition, many immigrants have a low calcium intake. Complaints may include fatigue, pain in shoulders, ribs, lower back and thighs. Neonates and young children may have spasms and convulsions due to hypocalcemia. Older children and adolescents may have bone pain, muscle weakness and skeletal deformities. Widening of the wrist, chest deformities and bowing of the legs may occur, and longitudinal growth is delayed. In adults, muscle weakness and bone pain are predominant. Laboratory examination may show hypocalcemia and hypophosphatemia and elevated alkaline phosphatase. The serum 25(OH)D is below 25 nmol/l in case of severe vitamin D deficiency with symptoms. Impaired 25-hydroxylation or 1α-hydroxylation may occur in case of severe liver or renal disease or by genetic causes. Radiographs of wrists or knees may show widening of the growth plates and cupping of radius and ulna may confirm the diagnosis. In adolescents and adults, radiographs of painful bones may show pseudofractures or Looser zones. Rickets and osteomalacia are treated by vitamin D3 2000 IU/d in infants, 3000–۶۰۰۰ IU/d in older children in combination with calcium 500 mg /d. In osteomalacia, the adult vitamin D3 dose is 2000–۳۰۰۰ IU/d, combined with calcium 1000–۲۰۰۰ mg/d. Prevention of vitamin D deficiency can be done with vitamin D3 400–۸۰۰ IU/d, depending on age. Nutritional measures include fortification of milk or other foods.

Introduction

Vitamin D deficiency is common in non-western immigrants and refugees. In this review, the specific features of vitamin D deficiency in this risk group will be discussed, including causes, consequences, prevention and treatment.

Case history

A Dutch-Moroccan woman of 29 years old comes to the clinic with complaints of pain with walking for 3 months, which started in December. The pain around her pelvic girdle and upper legs is increasing, and stair climbing becomes very difficult. In addition, she has pain around her shoulders. She has one child, now 6 months old. She wears a veil, when outside, and avoids sunshine in the middle of the day. She does not consume dairy products except for some yoghurt once or twice a week. Her child receives vitamin D drops after visiting a children’s clinic. Clinical examination reveals a healthy obese woman with weak upper leg muscles. She cannot rise from a chair without using her hands. On laboratory examination, the serum calcium in 1.96 mmol/l, phosphate 0.68 mmol/l, albumin 39 g/l, creatinine 85 μmol/l, alkaline phosphatase 175 U/l (ref limit < 120 IU/l). The serum 25-hydroxyvitamin D (25(OH)D) is below 5 nmol/l, the detection limit. The patient is treated with vitamin D3 800 IU/d, and when the serum 25(OH)D value becomes available, this is increased to 2000 IU/d and calcium 500 mg 3 tablets daily are added. The pain resolves within a week and muscle strength increases within weeks. After a month, stair climbing is no problem anymore. After 6 weeks, serum 25(OH)D is 54 nmol/l and the vitamin D dose is reduced to 800 IU/d.