Symptoms of Low Vitamin D
Low vitamin D primarily causes bone pain, muscle weakness, and increased risk of falls and fractures, though many individuals remain asymptomatic until severe deficiency develops.
Clinical Manifestations by Severity
Mild to Moderate Deficiency (Often Asymptomatic)
- Nonspecific symptoms including tiredness and general aches and pains are common but easily overlooked 1
- Many patients with vitamin D insufficiency (25-hydroxyvitamin D levels 30-50 nmol/L) have no obvious symptoms, making laboratory screening essential in at-risk populations 2
Severe Deficiency - Osteomalacia
- Aching bone pain that is symmetric and often affects the low back, ribs, and long bones - frequently misdiagnosed as fibromyalgia, chronic pain syndrome, or dismissed as depression 3, 4
- Proximal muscle weakness affecting the hips and shoulders, which impairs mobility and increases fall risk 5, 3
- Bone tenderness on palpation, particularly over the sternum, ribs, and tibiae 4
- Osteomalacia typically occurs when 25(OH)D levels fall below 10-12 ng/mL and is characterized by low calcium, low phosphorus, elevated alkaline phosphatase, and elevated PTH 6
Musculoskeletal Complications
- Increased risk of falls due to muscle weakness and impaired neuromuscular function 5, 3
- Osteopenia and osteoporosis develop as vitamin D deficiency precipitates and exacerbates bone loss 5, 3
- Fractures occur more frequently, particularly in elderly populations with combined vitamin D deficiency and low bone density 5, 3
Associated Clinical Findings
Laboratory Abnormalities
- Studies suggest associations with functional limitations, diabetes, and depression at lower 25(OH)D levels, though evidence is less consistent than for bone-related outcomes 2
- Secondary hyperparathyroidism develops as vitamin D insufficiency alters PTH regulatory mechanisms, further increasing osteoporosis and fracture risk 5, 4
Special Population Considerations
- Parkinson's disease patients with low vitamin D may experience accelerated disease progression and reduced bone mineral density, compounding their already elevated fracture risk from disease-related disability 2
- Chronic kidney disease patients (stages 3-5) have 80-90% prevalence of vitamin D insufficiency and are at particularly high risk for secondary hyperparathyroidism and bone disease 7
Critical Diagnostic Pitfall
The most important clinical caveat is that vitamin D deficiency is often a "silent" condition - the majority of patients with documented deficiency (25-hydroxyvitamin D ≤30 nmol/L) report no specific symptoms until severe complications like osteomalacia or fractures occur 8, 3. This is why screening based on risk factors rather than symptoms is essential, particularly in elderly individuals, those with darker skin pigmentation, homebound or institutionalized persons, and patients with malabsorptive conditions 2.