Symptoms of Vitamin D Deficiency in Adults
Vitamin D deficiency commonly presents with fatigue, muscle weakness, bone pain, muscle aches, and symmetric low back pain, with throbbing bone pain elicited by pressure over the sternum or tibia being particularly characteristic. 1, 2
Primary Clinical Manifestations
The most common symptoms include:
- Musculoskeletal pain: Symmetric low back pain and throbbing bone pain that can be elicited by applying pressure over the sternum or anterior tibia 2
- Muscle symptoms: Proximal muscle weakness, generalized muscle aches, and muscle fatigue 1, 3, 2
- Generalized symptoms: Fatigue and tiredness are frequently reported, though these are nonspecific 1, 4
- Increased fracture risk: Patients experience higher rates of falls and fractures, particularly in older adults 1, 3
Severe Deficiency Manifestations
In more severe cases, vitamin D deficiency can progress to:
- Osteomalacia in adults: A painful bone disease characterized by defective bone mineralization 3, 5
- Frailty syndrome in older adults: Contributing to sarcopenia, increased fall risk, physical disabilities, and reduced quality of life 1
Important Clinical Context
A critical pitfall is that mild vitamin D deficiency may not cause obvious symptoms initially, presenting only with subtle tiredness and general aches that are easily overlooked. 4 This makes clinical suspicion based on risk factors essential, as symptoms alone may not prompt evaluation until deficiency becomes more severe.
The American College of Physicians emphasizes that symptoms should be interpreted in the context of risk factors, including limited sun exposure, darker skin pigmentation, older age, obesity, malabsorptive conditions, and living at high latitudes 1, 3, 6
Diagnostic Approach
When these symptoms are present, particularly in high-risk individuals:
- Obtain serum 25-hydroxyvitamin D levels: Deficiency is defined as <20 ng/mL (50 nmol/L) 1, 2
- Consider seasonal timing: Older age combined with winter season are predictive factors for deficiency 1
- Recognize population-specific considerations: Total serum 25-(OH)D measurements may not accurately reflect vitamin D status in all populations, particularly African Americans, despite their having 2-9 times higher prevalence of low levels 7, 6