Prolactin Level Calculator

Endocrine Society Clinical Guidelines & Reference Ranges

Prolactin is a peptide hormone synthesized by anterior pituitary lactotroph cells under tonic inhibitory control by hypothalamic dopamine:

• Standard Reference Intervals:

• Non-Pregnant Adult Females: < 25 ng/mL

• Adult Males: < 20 ng/mL

• Pregnant Females: Up to 200--400 ng/mL (physiologic)

• Unit Conversion:

Prolactin = Prolactin × 21.2

Prolactin = Prolactin21.2

• Clinical Diagnostic Tiers:

• 25 to 100 ng/mL (Mild): Antipsychotics, antidepressants (SSRIs), metoclopramide, stress, hypothyroidism, PCOS, or stalk effect.

• 100 to 250 ng/mL (Moderate): Microprolactinoma (< 1 cm) or severe hypothyroidism.

• > 250 ng/mL (Severe): Pathognomonic for Macroprolactinoma (pituitary MRI indicated).

How to Use This Calculator

Enter your Prolactin Unit of Measure — select from ng/mL or µg/L (US Standard), mIU/L (International / SI Standard), Measured Serum Prolactin Level (e.g. 15), Patient Demographic & Reproductive Status — select from Non-Pregnant Female (Normal < 25 ng/mL), Adult Male (Normal < 20 ng/mL), Pregnant Female (Normal elevated up to 200–400 ng/mL), and Clinical Case Benchmark — select from Custom Lab Result, Normal Female (15 ng/mL / 318 mIU/L / Normal Range), Mild Elevation / Drug-Induced (45 ng/mL / 954 mIU/L). Results update instantly — no submit button needed. Use metric or imperial units as labeled. For the most accurate result, measure height and weight in the morning without shoes.

The Formula

Formula Reference: Prolactin Level Calculator

Input variables:

prolactinUnitSelect — Prolactin Unit of Measure

measuredProlactinValue — Measured Serum Prolactin Level

patientDemographicCategory — Patient Demographic & Reproductive Status

Computed outputs:

prolactinNgMlValue — Prolactin Level (ng/mL)

prolactinMiuLValue — Prolactin Level (mIU/L)

hyperprolactinemiaClassification — Clinical Severity Classification

pituitaryMriRecommendation — Pituitary MRI Sellar Imaging

differentialEtiologies — Differential Clinical Etiologies

Mathematical relationships extracted from calculation logic:

valNg = unit === 'miu_l' ? rawVal / 21.2 : rawVal

Reference constants:

normUpper = 25.0

Standard: WHO and CDC published clinical reference standards

Worked Example

A patient with irregular menses and a prolactin reading of 120 ng/mL is classified with Moderate Hyperprolactinemia, prompting a pituitary MRI that identifies a 6mm microadenoma.

Understanding Your Result

Health calculations based on standard clinical formulas give a population-reference estimate — individual variation exists. Compare your result to the reference ranges provided using validated sources (WHO, CDC, NIH, or specialty clinical guidelines). A single measurement is a starting point; meaningful health trends emerge from tracking the same metric over time under consistent conditions. For values outside reference ranges, consult a qualified healthcare provider before making changes to diet, exercise, or medication.