Comorbidities & Lab Workup in Vitiligo: Thyroid, Autoantibodies, Vitamin D, and a Practical Screening Algorithm

Key Takeaways

Autoimmune thyroid disease is the most frequent association; start with TSH and consider TPOAb in symptomatic or high-risk patients.
Screen selectively for B12/pernicious anemia, celiac disease (tTG-IgA + total IgA), and glucose/A1c based on history, age, and risk.
Vitamin D deficiency is common; replete per local guidelines (helps bone/skin health even if repigmentation impact varies).
Use a risk-stratified algorithm rather than blanket testing; repeat intervals depend on symptoms and prior results.

Symptoms: fatigue, weight change, heat/cold intolerance, palpitations, hair loss (thyroid); glossitis, paresthesias (B12); chronic diarrhea/iron deficiency (celiac); polyuria/polydipsia (glucose).
Family history: thyroid disease, type 1 diabetes, celiac, pernicious anemia, other autoimmune disorders.
Skin/hair: alopecia areata, nail changes; check for leukotrichia and active rims/confetti.

Table 1. Risk-stratified labs.

Risk tier	Who	Labs	Notes
Baseline (all)	Most adults/adolescents at diagnosis	TSH	Add TPOAb if symptoms/family history/goiter; reflex FT4 if TSH abnormal
Selective	Symptoms or risk factors present	TPOAb ± TgAb; Vitamin D (25-OH); Glucose or A1c; B12 ± MMA; tTG-IgA + total IgA	Choose based on history (GI/neurologic, iron-deficiency, weight change, dermatitis herpetiformis)
Extended	Atypical/multisystem signs	Ferritin/iron studies, CBC; consider ANA if systemic features	Coordinate with PCP/endocrinology/rheumatology as needed

Start with TSH. If abnormal, add FT4 (± FT3 per clinic) and anti-TPO; palpate thyroid.
Anti-TPO positive, normal TSH: counsel on symptoms; consider annual TSH or earlier if pregnant/planning pregnancy.
On treatment: follow endocrine protocols for TSH/FT4 intervals; coordinate care.

Table 2. When to order targeted tests.

Condition	Clues	Tests	Next steps
Pernicious anemia/B12 deficiency	Paresthesias, glossitis, macrocytosis, fatigue	Serum B12 (± MMA if borderline)	Replete B12; consider intrinsic factor Ab via PCP
Celiac disease	Chronic diarrhea, iron deficiency, dermatitis herpetiformis, FHx	tTG-IgA + total IgA (or DGP in IgA deficiency)	Positive → GI referral/biopsy per guidelines
Disordered glucose	Polyuria/polydipsia, weight loss, FHx diabetes	Fasting glucose or A1c	Abnormal → PCP/endocrinology follow-up
Autoimmune overlap	Arthralgia, photosensitivity, Raynaud’s, rash	Consider ANA only if systemic features	Rheumatology input if positive with symptoms

Who to test: limited sun exposure, darker phototypes in low-UV seasons, bone health risks, pediatrics, or patient preference.
Repletion: follow local protocols (e.g., cholecalciferol loading then maintenance); re-check 25-OH D as indicated.
Counseling: vitamin D supports general health; use NB-UVB decisions based on skin response, not vitamin D alone.

Pediatrics: prioritize history/exam; selective TSH; add targeted tests only with symptoms or FHx. See Pediatric Vitiligo.
Pregnancy/planning: strong case for TSH (and TPOAb if history); coordinate with OB/endocrine; ensure vitamin D adequacy per obstetric guidelines.

Table 3. Suggested intervals (adapt locally).

Test	If baseline normal	If borderline/positive	Red flags → action
TSH	q12–24 mo or sooner if symptoms	Per endocrine protocol	Tachycardia, severe fatigue, goiter → expedite endocrine
Vitamin D	Re-test only if repleted or at risk	After repletion course	Bone pain/fractures → PCP workup
B12	No routine repeat	Recheck after therapy	Neurologic deficits → urgent PCP/neurology
tTG-IgA	Not routine	GI referral if positive	Weight loss, anemia → GI workup

Document results in the vitiligo chart alongside F-/T-VASI and the photo protocol.