Dihydrotestosterone (DHT) is a potent androgen hormone derived from testosterone. DHT is created when the 5-alpha reductase enzyme converts a portion of circulating testosterone. Measuring the concentration of this hormone is possible and serves as a specialized tool for diagnosing and monitoring several medical conditions.
The Role of DHT in the Body
DHT is formed when the enzyme 5-alpha reductase acts on testosterone in specific tissues throughout the body. This conversion results in a steroid hormone significantly more potent than its precursor. During fetal development, DHT plays a specific role in forming the male external genitalia, including the penis and scrotum.
Later in life, DHT drives physical changes associated with male puberty, such as the growth of body hair, voice deepening, and prostate gland development. The hormone also influences sebaceous glands, contributing to oil production in the skin. Because it acts primarily within the tissues where it is produced, DHT functions mostly as a paracrine, or local, signaling molecule.
Clinical Triggers for DHT Testing
A healthcare provider may order a DHT test to investigate several conditions linked to androgen activity. One frequent reason is the evaluation of androgenic alopecia (male or female pattern hair loss), where DHT activity in the hair follicles is implicated in miniaturization. Testing can help support a diagnosis or rule out other causes of hair thinning.
Another primary indication is to assess for 5-alpha reductase deficiency, a rare genetic disorder, particularly in children presenting with ambiguous genitalia. In this condition, the enzyme responsible for converting testosterone to DHT is non-functional, leading to an elevation in the ratio of testosterone to DHT. The test is often performed during infancy or puberty when the hormonal axis is active.
In adults, the measurement monitors the effectiveness of anti-androgen medications, such as 5-alpha reductase inhibitors (e.g., finasteride) prescribed for benign prostatic hyperplasia (BPH) or hair loss. Measuring DHT levels before and after treatment provides an objective measure of the medication’s suppressive effect. Women presenting with signs of hyperandrogenism, such as excessive hair growth (hirsutism) or virilization, may also have their DHT levels checked as part of a comprehensive hormonal workup.
Methodology of DHT Measurement
Measuring Dihydrotestosterone circulating in the blood requires specialized and highly sensitive laboratory techniques. The most reliable method for quantification is Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). This advanced technology is preferred because it accurately measures the low concentrations of DHT found in serum or plasma.
Older testing methods, such as immunoassays, can produce inaccurate results due to cross-reactivity with similar steroid hormones. LC-MS/MS separates the DHT molecule from other compounds before measuring it, ensuring high specificity and precision. The blood sample for a DHT test is typically collected in the morning because the hormone exhibits diurnal variation, meaning its concentration fluctuates throughout the day.
The collected serum sample is processed through multiple steps, which may include liquid-liquid extraction and chemical derivatization. Due to the technical complexity and specialized equipment required, DHT testing is usually performed in reference laboratories rather than standard clinical labs. Results are reported in concentration units such as nanograms per deciliter (ng/dL) or nanomoles per liter (nmol/L).
Interpreting DHT Test Results
DHT test results are interpreted by comparing the patient’s concentration against established reference ranges, which differ based on age, sex, and the specific laboratory. For adult males, a typical reference range might fall between 30 and 85 ng/dL, but this range is substantially lower for women. The clinical significance of any result must always be considered alongside the patient’s symptoms and other hormone levels.
An elevated DHT level can indicate conditions where testosterone conversion is overactive, such as androgenic alopecia or benign prostatic hyperplasia. In women, an abnormally high level can signal hyperandrogenic states, including Polycystic Ovary Syndrome (PCOS). Extremely high values may warrant further investigation for rare androgen-producing tumors in the adrenal glands or testes.
Conversely, a low DHT level may suggest a deficiency in the 5-alpha reductase enzyme, confirmed by an elevated testosterone-to-DHT ratio. Low levels are also found in individuals with hypogonadism or in patients taking 5-alpha reductase inhibitor medications. The circulating blood level does not always perfectly reflect the hormone’s localized effect in target tissues like the prostate or hair follicles.