Calcium, Hair

Calcium, Hair (hair calcium analysis; hair mineral analysis for calcium) is ordered to assess extended calcium status within nutrition assessments. It may contribute to osteoporosis risk appraisal, especially in women with relevant risk factors, and can serve as an adjunct in the evaluation of autism spectrum disorder, fibromyalgia, and trichothiodystrophy. This assay is not intended for diagnosing acute disturbances of calcium metabolism, which are better evaluated with serum or urine testing.

Calcium is a major mineral required for cell membrane function, bone mineralization, neurotransmission, hormone secretion, muscle contraction, and coagulation. Approximately 99% of total body calcium is stored in bone as hydroxyapatite, with less than 1% distributed in extracellular fluid and within cells. Systemic balance depends on dietary intake and is regulated by parathyroid hormone, vitamin D, and calcitonin. Scalp hair accumulates calcium and other elements over an estimated 6–8-week interval, creating a retrospective matrix that can mirror longer-term mineral status. Collection is painless, which can be advantageous in pediatric populations. Lower hair calcium has been associated with reduced bone mineral density in women of reproductive age and has been reported in individuals with autism spectrum disorder and in those with fibromyalgia despite normal serum calcium. In fibromyalgia, diminished hair calcium may signify intracellular deficiency and correlate with muscle-related symptoms. Hair mineral analysis has limited dermatologic applications but can aid evaluation of rare conditions such as trichothiodystrophy. Hair analysis does not diagnose acute calcium derangements, and interpretation is constrained by interindividual variability related to intrinsic hair characteristics. Results should be considered alongside the clinical picture and other laboratory data.