Symptoms of Vitamin D Deficiency
Vitamin D deficiency commonly presents with fatigue, weakness, bone pain, muscle aches, and increased risk of fractures, and should be suspected in patients with these symptoms, particularly those with risk factors for low vitamin D levels. 1
Common Clinical Manifestations
- Fatigue and generalized weakness are frequently reported symptoms of vitamin D deficiency 1, 2
- Muscle aches and proximal muscle weakness that can affect mobility and balance 3
- Symmetric low back pain and throbbing bone pain that can be elicited with pressure over the sternum or tibia 3
- Bone pain that may be misdiagnosed as fibromyalgia or chronic pain syndrome 4
- Increased risk of falls due to neuromuscular dysfunction and muscle weakness 5
Severe Manifestations
- Osteomalacia in adults - a painful bone disease characterized by inadequate mineralization of bone matrix 2, 4
- Osteopenia and osteoporosis, with increased risk of fractures 2, 4
- Secondary hyperparathyroidism due to altered regulatory mechanisms of parathyroid hormone 2, 5
- In children, rickets can develop, causing visible skeletal deformities 1, 6
Laboratory Findings
- Serum 25-hydroxyvitamin D level below 20 ng/mL (<50 nmol/L) is defined as vitamin D deficiency 1, 3
- Levels between 20-30 ng/mL (50-75 nmol/L) are considered vitamin D insufficiency 3
- In severe cases, low serum calcium and phosphorus levels may be present 1
- Elevated parathyroid hormone levels may indicate secondary hyperparathyroidism 5
High-Risk Populations
- Individuals with limited sun exposure or who routinely wear clothing that prevents sun exposure 7
- People with darker skin pigmentation (African Americans, Hispanics, and Asians) 7
- Older adults due to age-related decrease in cutaneous vitamin D synthesis 7, 6
- Patients with malabsorptive conditions, inflammatory bowel disease, or history of gastric bypass 7, 1
- Obese individuals (possibly due to sequestration of vitamin D in adipose tissue) 7
- Homebound or institutionalized persons 7
- Those living at high latitudes with reduced UVB exposure 7
Systemic Effects Beyond Bone Health
- Increased risk of cardiovascular disease in some populations 7, 6
- Potential association with diabetes mellitus 7, 6
- Possible link to depression and other mood disorders 7
- Increased susceptibility to infections and autoimmune disorders 6
- Sleep disturbances 6
Clinical Pitfalls to Avoid
- Failing to consider vitamin D deficiency in patients with nonspecific musculoskeletal complaints 3
- Misdiagnosing vitamin D deficiency-related pain as fibromyalgia or depression 4
- Not recognizing that vitamin D requirements vary by individual based on risk factors 1
- Overlooking that laboratory reference ranges for vitamin D may not reflect optimal levels for health 2
- Not considering that total serum 25-(OH)D measurements may not accurately reflect vitamin D status in all populations, particularly African Americans 7