QUICK ANSWER
"PROLACTIN, SERUM" is the LabCorp test label for the serum prolactin measurement. It is identical in clinical meaning to a standard prolactin blood test — the label difference is a naming convention, not a different test.
Normal range:
- Men: < 20 ng/mL (< 424 mU/L)
- Women (non-pregnant): < 25 ng/mL (< 530 mU/L)
- Women (pregnant): 80–400 ng/mL
For a complete guide including causes of elevated prolactin, the prolactinoma threshold, macroprolactinemia, drug effects, and the interpretive matrix with LH, FSH, and testosterone, see the full Prolactin guide.
Key takeaway: A result labelled "PROLACTIN, SERUM" on a LabCorp report is interpreted identically to any other prolactin result. The most important questions are: Is the value above the reference range? Are symptoms present? Has TSH been checked?
NORMAL RANGE FOR PROLACTIN, SERUM
| Group | Normal range (ng/mL) | Normal range (mU/L) |
|---|---|---|
| Adult male | 2.0–18.0 | 42–382 |
| Adult female (non-pregnant) | 3.0–30.0 | 64–638 |
| Adult female (pregnant) | 10.0–209.0 | 212–4,440 |
| Adult female (postmenopausal) | 2.0–20.0 | 42–424 |
Unit note: The LabCorp PROLACTIN, SERUM test reports in ng/mL. If your report shows μg/L, the values are identical to ng/mL (1 ng/mL = 1 μg/L). To convert to mU/L: multiply ng/mL by 21.2.
WHAT DOES A HIGH PROLACTIN, SERUM RESULT MEAN?
High PROLACTIN, SERUM (above the reference range for your sex and reproductive status) indicates hyperprolactinemia. The clinical interpretation is the same regardless of which lab label is used.
Common causes of elevated prolactin:
- Physiological: pregnancy, breastfeeding, stress, recent exercise, nipple stimulation
- Medications: antipsychotics (especially risperidone), metoclopramide, antidepressants, opioids
- Prolactinoma (benign pituitary tumour) — the most common cause of persistent significant elevation
- Hypothyroidism — always check TSH alongside elevated prolactin
- Macroprolactinemia — benign condition present in ~20% of elevated results; no symptoms despite high measured levels
- PCOS, renal failure, liver disease
When to follow up: Persistent elevation above the reference range on a repeat fasting sample, elevation > 100 ng/mL, or any elevation accompanied by symptoms (irregular periods, galactorrhoea, infertility, low libido, headaches, visual changes).
For detailed level-by-level interpretation, the full causes list, macroprolactinemia explanation, drug-specific thresholds, and the interpretive matrix with LH, FSH, TSH, and testosterone — see the complete guide: Prolactin: What High, Low & Normal Levels Mean
WHAT DOES A LOW PROLACTIN, SERUM RESULT MEAN?
Low prolactin (below the reference range) is uncommon and usually indicates partial pituitary insufficiency. In non-pregnant adults it typically causes no specific symptoms requiring treatment. In new mothers, low prolactin impairs milk production and may indicate Sheehan syndrome (pituitary damage from postpartum haemorrhage).
INTERNAL LINKS
Primary guide: Prolactin: What High, Low & Normal Levels Mean — complete guide including prolactinoma thresholds, macroprolactinemia, drug effects, and interpretive matrix with LH, FSH, TSH, and testosterone.
Related tests: TSH · LH · FSH · Estradiol · Testosterone
Prolactin
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Frequently Asked Questions
What is "PROLACTIN, SERUM" on a lab report?
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What does high PROLACTIN, SERUM mean?
What is the difference between ng/mL and μg/L on a prolactin report?
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