Acne in Adults: The Hormonal, Vitamin, and Metabolic Lab Checklist

Adult acne is not something you simply "grow out of." Between 40% and 55% of people over 25 experience persistent breakouts on the face, back, or chest, and the cause goes well beyond "bad skin." Chronic acne in adults almost always involves a combination of hormonal imbalance, diet, gut health, and deficiencies in vitamins and minerals. The good news is that nearly all of these factors are visible on blood work.

This article provides a complete checklist of blood tests for acne: the hormonal profile (testosterone, DHEA-S, SHBG — and for women LH/FSH, estradiol, 17-OH progesterone), vitamin D and zinc, CBC with a metabolic panel, insulin and HOMA-IR for suspected insulin resistance, plus H. pylori screening. We explain which signs point to a hormonal root cause, how to prepare, and when to see a doctor.

Disclaimer: This information is for educational purposes only and does not replace professional medical advice. If you have deep, painful, nodular or cystic acne with a risk of scarring, do not delay seeing a dermatologist — modern treatment can quickly control inflammation and prevent permanent marks.

Why Adults Get Acne

Acne is a multifactorial disease of the sebaceous glands and hair follicles. Four main mechanisms drive it:

• Excess sebum production under the influence of androgens (male sex hormones present in all genders).
• Follicular plugging by dead skin cells (hyperkeratinization).
• Overgrowth of Cutibacterium acnes bacteria in the oxygen-deprived environment of a blocked pore.
• Inflammation and immune response to sebum components and bacterial metabolites.

Layered on top of these mechanisms are:

• Hormonal imbalances — especially in women (PCOS, adrenal or ovarian androgen excess, non-classic congenital adrenal hyperplasia).
• Insulin resistance — high insulin drives androgen synthesis and insulin-like growth factor (IGF-1), both of which fuel sebaceous glands.
• Vitamin D and zinc deficiency.
• Gut inflammation, dysbiosis, or H. pylori infection.
• Chronic stress and poor sleep — cortisol elevation and proinflammatory cytokine release.

Each of these factors can be tested in the lab. And this is exactly why treating chronic adult acne with topical products alone is rarely sufficient.

The Baseline Acne Lab Panel

This is the minimum worth ordering first. Suitable for both men and women.

1. Complete Blood Count (CBC) With Differential

Reveals whether overt inflammation, anemia, or infection is present:

• Hemoglobin and RBC count — anemia frequently accompanies acne in women.
• WBC differential — lymphocytes, neutrophils, monocytes, eosinophils.
• ESR — a general inflammation marker.

For a detailed breakdown, see our CBC interpretation guide.

2. Basic Chemistry: ALT, AST, Bilirubin, Glucose

The liver metabolizes sex hormones and indirectly influences acne. Undetected fatty liver or drug-induced liver injury can sustain breakouts. Glucose provides the first hint of carbohydrate metabolism problems.

• ALT and AST — generally up to 40 U/L (slightly higher in men).
• Fasting glucose: normal 70-99 mg/dL (3.9-5.5 mmol/L). 100-125 mg/dL = prediabetes.

For a comprehensive panel walkthrough, see our blood chemistry guide.

3. Vitamin D (25-OH)

Vitamin D deficiency is especially common in acne patients and is associated with more severe inflammatory forms.

• Normal: 30-60 ng/mL.
• Insufficiency: 20-30 ng/mL.
• Deficiency: below 20 ng/mL.

Correcting vitamin D deficiency is simple, safe, and often visibly improves acne within 2-3 months. Dosing is determined by your physician.

4. Serum Zinc

Zinc is a key trace element for sebaceous gland function and the skin's anti-inflammatory defense. Its deficiency is directly associated with acne and poor healing.

• Reference range: 60-120 mcg/dL (11-20 mcmol/L).
• Signs of deficiency: slow healing, frequent colds, brittle hair and nails, altered taste.

5. Ferritin

Latent iron deficiency affects skin collagen synthesis and immune function. In women with heavy periods, this is an essential marker.

• Reference range: men 30-400 ng/mL, women 15-150 ng/mL. Optimal for well-being: above 50-70 ng/mL.

The Hormonal Profile for Acne

A hormonal cause of acne is especially likely if:

• Breakouts concentrate along the jawline, chin, and neck — less often the back and chest.
• Flare-ups clearly correlate with the menstrual cycle (5-7 days before or during).
• There are irregular periods, infertility, or excess body or facial hair (hirsutism).
• Acne appeared or worsened after stopping hormonal contraceptives.
• Acne coexists with an oily scalp, dandruff, and hair loss (androgenetic alopecia).

For Women

Draw on cycle days 2-5 unless otherwise noted:

• Total testosterone — reference range 15-70 ng/dL (0.5-2.4 nmol/L).
• Free testosterone — the biologically active fraction, a more precise marker.
• DHEA-S — the principal adrenal androgen. Elevation points to an adrenal source.
• SHBG — sex hormone-binding globulin. The lower the SHBG, the higher the free androgens at a given total testosterone. Reference range: 27-146 nmol/L.
• Free androgen index (FAI) — (total testosterone / SHBG) x 100. Normal for women: below 5%.
• LH and FSH — on days 2-5. An LH/FSH ratio above 2 is a common PCOS marker.
• Estradiol — primary female hormone.
• 17-OH progesterone — to rule out non-classic congenital adrenal hyperplasia. Normal on days 2-5: up to 200 ng/dL.
• Progesterone — on day 21-23, to evaluate ovulation.
• Prolactin — elevation can secondarily disrupt the sex hormone balance.

For Men

• Total testosterone — reference range 300-1000 ng/dL.
• Free testosterone — for clarification.
• DHEA-S.
• SHBG.
• Estradiol — elevation in men is also associated with acne.
• Prolactin.

Thyroid Hormones

Both hypothyroidism and hyperthyroidism can secondarily affect the skin:

• TSH — reference range 0.4-4.0 mIU/L.
• Free T4 — reference range 0.8-1.8 ng/dL.
• Free T3.

For more, see our thyroid test interpretation guide.

Insulin and Insulin Resistance

High insulin stimulates androgen synthesis and IGF-1, both of which amplify sebaceous gland output. This is particularly relevant with a high-sugar diet, excess weight, or PCOS.

• Fasting glucose.
• Fasting insulin — reference range 2.6-24.9 mcIU/mL, but functional optimum is below 10 mcIU/mL.
• HOMA-IR = (glucose in mg/dL x insulin) / 405. Normal: below 2.0 (some labs use 2.5). Elevated = insulin resistance.
• HbA1c — normal below 5.7%.

Gut Health Check

Hidden gut inflammation, dysbiosis, and H. pylori infection can perpetuate skin breakouts.

H. pylori Screening

Primary methods available through Quest Diagnostics, LabCorp, or Synlab:

• Urea breath test (13C) — the gold standard for non-invasive H. pylori diagnosis.
• H. pylori stool antigen test — convenient and accurate (sensitivity around 95%).
• H. pylori IgG serology — may remain positive after successful treatment, so less preferred for initial diagnosis.

A positive result warrants referral to a gastroenterologist for eradication therapy.

hsCRP — High-Sensitivity C-Reactive Protein

A marker of systemic low-grade inflammation. If elevated with a clean CBC, an inflammatory process is smoldering somewhere — possibly in the gut, or an autoimmune condition.

How to Prepare

1. Blood drawn in the morning, fasting — 8-12 hours without food. Water is fine.
2. Avoid alcohol for 24 hours.
3. No smoking for 2 hours before the draw.
4. No intense exercise for 24 hours.
5. Sex hormones — strictly on the correct cycle day.
6. Hormonal contraceptives — discuss temporary discontinuation with your doctor, as they significantly affect results.

How to Read Your Results

• Isolated elevation of total testosterone in a woman — investigate further with SHBG, DHEA-S, 17-OH progesterone, and a pelvic ultrasound.
• Elevated DHEA-S — points to an adrenal source of androgen excess.
• LH/FSH ratio above 2 + elevated testosterone + polycystic ovaries on ultrasound — classic PCOS pattern.
• Low vitamin D + low zinc — a typical picture in chronic inflammatory acne.
• HOMA-IR above 2.0 + excess weight + PCOS — insulin resistance, requires dietary intervention and possibly metformin (physician-guided).
• Elevated hsCRP with a normal CBC — look for a hidden inflammatory focus, including the gut.

For a comprehensive analysis of your panel, upload your results at Evallume — the AI-powered interpretation will evaluate your hormones, vitamins, insulin resistance index, and inflammatory markers together, highlighting suspicious combinations and suggesting what to discuss with your dermatologist and endocrinologist.

When to See a Doctor

See a dermatologist without delay if:

• Breakouts are deep, painful, and leaving scars.
• New cysts or nodules appear weekly.
• Acne has spread to the back, shoulders, and chest.
• Standard skincare has not helped for more than 2-3 months.
• Acne appeared suddenly in adulthood without an obvious trigger.

See an endocrinologist or gynecologist if labs reveal:

• Elevated testosterone, DHEA-S, or 17-OH progesterone.
• Irregular periods, hirsutism, or PCOS markers.
• Insulin resistance.
• Thyroid dysfunction.

See a gastroenterologist if H. pylori is confirmed or there are persistent digestive complaints alongside skin issues.

Adult acne is not just cosmetic — it signals that hormones, metabolism, and the inflammatory system are out of balance. Blood work lets you see the system as a whole and direct treatment where it will actually work. For a broader baseline health check, also see our guide to annual health checkup blood tests.

This article is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Consult a healthcare professional for any medical concerns.