Effective hair loss treatment starts with one question that is too often skipped: why is the hair thinning? Hair loss is a symptom, not a single condition — and the right treatment depends entirely on the underlying cause. As a physician, Dr. Susan Lin begins every hair-loss evaluation here.

The most common medical causes

  • Genetic (androgenetic) hair loss — the most common type in both men and women, driven by inherited sensitivity to hormones.
  • Hormonal changes — pregnancy, menopause, and thyroid disorders can all trigger shedding.
  • Thyroid and other medical conditions — an underactive or overactive thyroid is a frequently missed contributor.
  • Nutritional deficiencies — low iron (ferritin) and vitamin D in particular.
  • Stress and illness — physical or emotional stress can cause temporary shedding (telogen effluvium), as seen after COVID.
  • Medications — certain drugs list hair loss as a side effect.

Why diagnosis matters

Each of these causes responds to a different approach. Genetic thinning may benefit from PRP and targeted therapies; a thyroid or iron issue needs the underlying problem corrected first. Treating the wrong cause wastes time during the window when hair is most recoverable.

A physician-led evaluation

At MD Laser & Cosmetics in San Mateo, Dr. Lin reviews your history, may recommend relevant lab work, and builds a plan around the actual cause — which may combine in-office PRP, scalp health treatments, the physician-formulated MD® hair line, and nutritional guidance. Hair loss treatment plans start at $500.

Frequently Asked Questions

How do I find out what is causing my hair loss?

A physician evaluation — including your history and, when appropriate, lab tests for iron, thyroid, and vitamin D — identifies the underlying cause so treatment can target it.

Can hair loss from a medical cause be reversed?

Often, yes — especially when caught early and when the underlying cause (such as a deficiency or thyroid issue) is corrected. Results take several months.

Is hair loss in women different from men?

The pattern and some causes differ. Women more often have diffuse thinning and are more prone to iron-related shedding. Dr. Lin tailors evaluation accordingly.

Want to understand what is really causing your hair loss? Every treatment at MD Laser & Cosmetics is performed personally by Dr. Susan Lin, M.D. Learn more or book a consultation.