Vitamin D deficiency in risk groups living in tropical Curaçao

Curaçao (12 degrees 10ON, 69 degrees OW) is characterized by whole year abundant sunshine (8-10 hours/day). We challenged the automatic assumption that people living in tropical countries do not have a high risk of vitamin D deficiency, and investigated the vitamin D status in a tropical environment.

For this, we selected fifty-two elderly people with little or no exposure to direct sunlight [median 84 (60-96) years; 34females, 18 males] and who were cared for by community nurses or lived in retirement or nursing homes. Furthermore, six rehabilitating orthopaedic patients [median 72 (38-90) years; one female, five males] were included. Serum 25(OH)D, calcium, phosphate, parathyroid hormone (PTH) and creatinine were measured. Those exhibiting elevated creatinine, PTH or both had their 1,25-dihydroxyvitamin D [1,25(OH)2D] examined.

Serum levels of 25(OH)D below 25, 50 and 75 nmol/L were detected in, respectively, seven (12%), 22 (38%) and 48 (83%) ofthe fifty-eight persons. Four persons had combined high creatinine and PTH, and low 1,25(OH)2D, which was not known by their caregivers.

Abundant sunshine outdoors is no guarantee for vitamin D sufficiency. More attention is needed for vitamin D deficiency in risk groups living in tropical areas and elderly persons with poor kidney function.