Diagnosis of Vitamin D Deficiency

The main manifestation of vitamin D deficiency in adults is osteomalacia.¹

Less severe vitamin D deficiency, sometimes termed vitamin D insufficiency, may lead to secondary hyperparathyroidism, bone loss, muscle weakness, falls and fragility fractures in older people.¹

• Symptoms of vitamin D deficiency can include:
• Unexplained fatigue²
• Difficulty thinking clearly³
• Bone pain⁴
• Muscle weakness⁴
• Soft bones that may result in deformities⁴

When a child or adult suffers from vitamin D deficiency, they are unable to absorb sufficient calcium from their diet. This increases the levels of parathyroid hormone (PTH). In an attempt to restore calcium levels in the blood, which is needed for vital metabolic and neuromuscular processes, PTH acts to remove calcium from the skeleton.⁵

Measuring vitamin D levels

If someone is in one of the ‘at risk’ groups or has symptoms suggesting a potential vitamin D deficiency, the best way to confirm a diagnosis is through direct measurement of plasma 25(OH)D.¹

The reference ranges used by the Royal Osteoporosis Society (ROS) are as follows. These ranges also align with thresholds identified by ROS.¹

• plasma 25(OH)D < 25 nmol/L is deficient
• plasma 25(OH)D of 25–50 nmol/L may be inadequate in some people
• plasma 25(OH)D > 50 nmol/L is sufficient for almost the whole population