Vitamin D Status and Test Utilization: A Five-Year Analysis.

Background Vitamin D testing has increased markedly over the past decade, often exceeding evidence-based recommendations that discourage routine screening in low-risk populations. This growing demand has raised concerns regarding test overutilization, misalignment with clinical indications, and the uncertain impact on patient management. This study aimed to assess vitamin D status, clinical indications for testing, and associated comorbidities over a five-year period in North Batinah, Oman, while evaluating the clinical utility of vitamin D testing in routine practice. Methodology A retrospective cross-sectional study included all vitamin D requests by the primary healthcare institutes sent to Sohar Hospital, the sole regional laboratory providing serum 25-hydroxyvitamin D (25(OH)D) testing. All Omani and non-Omani residents who underwent testing between January 2018 and November 2022 were included. Vitamin D status was classified as deficient (<30 nmol/L), insufficient (30-50 nmol/L), or sufficient (>50 nmol/L). Demographic variables, documented clinical indications, and comorbidities, including diabetes mellitus, hypertension, anemia, chronic kidney disease, and hypothyroidism, were analyzed, alongside temporal trends in testing patterns. Results A total of 3,081 patients were included, predominantly women and Omani nationals. Overall, vitamin D sufficiency was high across the cohort. However, vitamin D insufficiency was more prevalent among younger and middle-aged adults, particularly women, whereas older adults demonstrated higher sufficiency rates. Pediatric vitamin D deficiency was uncommon, though adolescents showed increased rates of insufficiency. A substantial proportion of vitamin D test requests were not aligned with guideline-supported clinical indications. Among individuals with low vitamin D levels, anemia, hypertension, and hypothyroidism were the most frequently observed comorbidities, while diabetes mellitus did not demonstrate a strong association. Conclusion Despite increasing testing volumes, clinically significant vitamin D deficiency was relatively uncommon, suggesting the potential overutilization of testing. These findings highlight the need for targeted, indication-based vitamin D testing strategies and strengthened laboratory stewardship to improve clinical value and optimize healthcare resource utilization.