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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Hyperprolactinaemia and hypothalamic amenorrhoea

Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Escalate neurological or nutritional instability

Acute severe headache, visual loss or ophthalmoplegia may be pituitary apoplexy, while bradycardia, hypotension, orthostasis, electrolyte disturbance or syncope may reflect life-threatening energy deficiency.

Action: Use an ABCDE assessment, check glucose and electrolytes, obtain urgent cortisol and specialist pituitary input for neurological presentations, and admit medically unstable restrictive-eating or exercise-related illness.

Overview

Distinguish prolactin-mediated from functional hypothalamic reproductive suppression, detect pituitary and nutritional emergencies, and restore fertility, oestrogen exposure and bone health safely.

Prolactin excess and functional hypothalamic amenorrhoea both reduce pulsatile hypothalamic reproductive signalling, but one begins with excessive lactotroph activity or lost dopamine inhibition and the other with an adaptive response to inadequate energy, exercise, stress or illness. Both can present without a classic clue: galactorrhoea is neither necessary nor specific for hyperprolactinaemia, and a normal BMI does not exclude low energy availability. Ask about pregnancy, lactation, medicines, breast or chest stimulation, weight trajectory, intake, exercise, sleep, stress, fracture and neurological symptoms.

A single modest prolactin can rise from venepuncture stress. Repeat under calm conditions and review the laboratory's macroprolactin process when symptoms and result disagree. Check pregnancy, TSH with free T4, renal and liver function and causative medicines before imaging. Do not stop an antipsychotic abruptly: work with psychiatry to balance mental-health relapse, substitution and endocrine harm. Persistent biologically active elevation, a marked value or mass symptoms leads to full pituitary testing, MRI and formal fields when the chiasm is threatened.

Practice

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Obstetrics and gynaecologyOriginal SBA

Hyperprolactinaemic ovulatory treatment

A patient has persistent true hyperprolactinaemia causing anovulation after pregnancy, medicine, thyroid and renal causes have been addressed. Which treatment does NICE NG257 recommend?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG257 female fertility management
  • Cabergoline UK SmPC
  • Endocrine Society hypothalamic amenorrhoea guideline
  • NICE eating disorders guidance
  • University Hospitals Sussex cabergoline information

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

Interpret prolactin against imaging volume. Stalk compression raises prolactin by interrupting dopamine delivery, usually less dramatically than a secreting macroprolactinoma. At extremely high concentrations, a two-site assay can saturate and report a falsely modest result: request serial dilution when a giant lesion and value do not match. Check morning cortisol urgently when a large lesion or acute illness suggests ACTH deficiency; a normal reproductive work-up does not make cortisol failure safe.

Cabergoline is an effective dopamine agonist that lowers prolactin, shrinks most prolactinomas and restores ovulation. NICE NG257 specifically offers it for ovulatory disorder due to hyperprolactinaemia. Start low with food and titrate to the lowest effective specialist dose, monitoring postural symptoms, nausea, somnolence, impulse-control or psychiatric change and fibrotic or valvular risk under current product guidance. Ovulation may precede the first period, so establish contraception or a preconception plan at initiation.

Functional hypothalamic amenorrhoea is diagnosed only after excluding pregnancy, PCOS, POI, thyroid and prolactin disease, systemic illness and structural causes. Low oestradiol with low or inappropriately normal LH and FSH supports central suppression. Take an open account of eating, training, injuries, perfectionism, anxiety, weight change and food access. Check observations and systemic bloods, and use DXA after six months of amenorrhoea or earlier with severe nutritional deficit, fragility or stress fracture.

Treatment restores energy availability rather than merely manufacturing a bleed. Increase nutritional intake, reduce excessive energy expenditure and use psychological therapy such as CBT through a multidisciplinary team. Eating-disorder care may be required even without low weight. Combined contraception can conceal spontaneous cycle recovery and has not corrected ongoing bone loss from energy deficit; do not use it solely for bone or menstrual restoration. Contraception may still be chosen for contraceptive reasons after explaining this limitation.

If menstruation remains absent after a reasonable trial of nutritional, exercise and psychological intervention, a specialist may offer short-term transdermal 17β-oestradiol with cyclic oral progestogen for bone and symptom support. For pregnancy, complete the fertility assessment and normalise energy balance first; the Endocrine Society advises ovulation induction only when BMI is at least 18.5 kg/m² because very low weight increases obstetric risk. Pulsatile GnRH is physiologically attractive where available, with gonadotrophins an alternative requiring careful monitoring.

Key points

  • Both disorders suppress GnRH and can cause oligomenorrhoea, amenorrhoea, anovulation, infertility, low libido and bone loss, but their causal signals and treatment are different.
  • Confirm true prolactin excess after excluding pregnancy, lactation, stress, macroprolactin, primary hypothyroidism, renal or hepatic disease and medicines such as antipsychotics, metoclopramide, domperidone and opioids.
  • Repeat a modest prolactin under calm conditions and ask the laboratory about macroprolactin; request dilution when tumour volume is disproportionate to the reported value.
  • NICE NG257 recommends cabergoline for ovulatory disorders due to hyperprolactinaemia; the current SmPC starts 0.5 mg weekly in one or two doses with gradual specialist titration.
  • Functional hypothalamic amenorrhoea is a diagnosis of exclusion linked to low energy availability, exercise load, stress or illness and can occur at any BMI.
  • Correct energy imbalance with increased intake, reduced exercise where needed and psychological support; weight gain is often necessary, but menstruation is not the only recovery marker.
  • Do not prescribe a combined oral contraceptive solely to restore periods or improve bone density in hypothalamic amenorrhoea because it can mask recovery while energy deficit persists.

Aetiology

01

Autonomous prolactin secretion

A lactotroph pituitary adenoma releases prolactin independently and may also create mass effect as a microadenoma enlarges.

02

Reduced dopamine restraint

Dopamine-antagonist medicines or pituitary-stalk interruption remove tonic hypothalamic inhibition and raise prolactin without a secreting adenoma.

03

Low energy and stress

Inadequate energy availability, excessive exercise, psychological stress or illness adaptively reduces hypothalamic reproductive signalling in functional amenorrhoea.

04

Physiological and systemic prolactin

Pregnancy, lactation, hypothyroidism, renal impairment, liver disease and chest stimulation can raise prolactin and require contextual interpretation.

Pathophysiology

  1. 1
    GnRH pulses are suppressed

    Excess prolactin or hypothalamic adaptation reduces pulsatile reproductive signalling and therefore LH and FSH support for ovarian follicles.

  2. 2
    Oestradiol production falls

    Inadequate gonadotrophin stimulation impairs follicular maturation, ovulation and luteal function, producing low or fluctuating oestrogen exposure.

  3. 3
    Bone remodelling increases

    Hypo-oestrogenism, undernutrition and exercise-related hormonal changes reduce bone formation or accelerate loss, predisposing to stress and fragility fractures.

  4. 4
    Tumour compression develops

    A macroadenoma can contact the optic chiasm, impair other pituitary axes or rarely reveal a skull-base defect during rapid shrinkage.

Clinical features and red flags

Prolactin-mediated hypogonadism

Cycle change, infertility, low libido or vaginal dryness with true monomeric prolactin excess can occur with or without galactorrhoea.

Pituitary mass effect

Headache, bitemporal field loss, colour-vision change, diplopia, cortisol symptoms or polyuria suggests broader sellar disease rather than isolated reproductive dysfunction.

Low-energy phenotype

Restricted intake, high training volume, stress injury, weight loss, bradycardia or preoccupation with food and exercise supports hypothalamic suppression at any BMI.

Central hormone pattern

Low oestradiol with low or inappropriately normal gonadotrophins fits functional or organic central hypogonadism after prolactin and pituitary causes are evaluated.

Bone consequence

Stress fracture, loss of height or delayed peak bone acquisition signals clinically important hypo-oestrogenism and nutritional deficiency even before osteoporosis is measured.

Red flags requiring action

  • Sudden severe headache, visual loss, ophthalmoplegia, vomiting or reduced consciousness requires emergency assessment for pituitary apoplexy and cortisol deficiency.
  • Progressive bitemporal field loss, diplopia or persistent headache with hyperprolactinaemia requires expedited pituitary MRI and visual assessment.

Investigations

  1. 01
    Repeat prolactin with macroprolactinFirst step
    Why
    Confirm persistent biologically relevant prolactin excess after reducing transient sampling effects.
    Interpretation and limitations
    A stress-related modest rise may normalise; predominant macroprolactin can explain laboratory elevation with fewer biological effects, while persistent monomeric elevation needs causal assessment.
  2. 02
    Pregnancy, thyroid, renal and liver tests
    Why
    Identify physiological and systemic explanations before attributing prolactin elevation to a tumour.
    Interpretation and limitations
    Pregnancy and lactation change reference interpretation, primary hypothyroidism increases prolactin drive and reduced renal clearance can elevate the measured concentration.
  3. 03
    Diluted prolactin and pituitary MRI
    Why
    Resolve a tumour-hormone mismatch and define sellar anatomy when imaging is indicated.
    Interpretation and limitations
    A large rise after assay dilution reveals hook effect; MRI size, chiasmal contact and stalk anatomy must be correlated with prolactin and the complete pituitary profile.
  4. 04
    LH, FSH and oestradiol
    Why
    Document central hypo-oestrogenism and distinguish it from ovarian insufficiency.
    Interpretation and limitations
    Low oestradiol with non-raised gonadotrophins supports hypothalamic or pituitary suppression; raised FSH instead redirects assessment toward POI.

Differential diagnosis

01

Primary ovarian insufficiency

Low oestradiol with raised rather than suppressed gonadotrophins indicates loss of ovarian feedback and uses a separate replacement and genetic pathway.

02

Polycystic ovary syndrome

Ovulatory dysfunction with hyperandrogenism and usually preserved oestrogen differs from low-energy central suppression, although ovarian morphology can overlap.

03

Medicine-induced hyperprolactinaemia

Antipsychotics, antiemetics and opioids may produce a coherent prolactin rise, but treatment changes require collaboration and tumour evidence still matters.

04

Organic hypothalamic-pituitary disease

Tumour, inflammation, infiltration, trauma or multiple pituitary deficiency can mimic functional suppression and is suggested by neurological or additional hormone features.

Management

01Raised prolactinConfirm before imagingFirst stepProlactin is above the laboratory range in a person with cycle disturbance.+
  1. 1Check pregnancy, lactation, stress, chest stimulation, thyroid, renal and hepatic status and every dopamine-antagonist or opioid medicine.
  2. 2Repeat a modest elevation and request macroprolactin; arrange diluted assay urgently when a large sellar lesion is discordant with the concentration.
  3. 3Refer persistent true elevation or mass symptoms for pituitary profile, MRI, visual assessment and cause-directed endocrine care.
02CabergolineRestore ovulation and control tumour safelyHyperprolactinaemic ovulatory disorder or prolactinoma merits dopamine-agonist treatment.+
  1. 1Discuss fertility, contraception, pregnancy, cardiac and fibrotic history, postural effects, mental health and interacting medicines before the first dose.

Complications

01

Infertility

Suppressed follicular maturation and ovulation reduce conception, although successful cause treatment can restore fertility before periods become regular.

02

Low bone strength

Prolonged hypo-oestrogenism combined with nutritional deficiency increases stress fracture, low measured density and future skeletal fragility risk.

03

Visual and pituitary loss

An enlarging sellar tumour can damage optic pathways and compress ACTH, TSH or other pituitary secretion with cortisol deficiency carrying acute risk.

04

Pregnancy and treatment harm

Conception during poor energy status or unplanned medicine exposure raises maternal and fetal risk and complicates tumour monitoring.

Monitoring and follow-up

  • For hyperprolactinaemia, follow prolactin, symptoms, gonadal recovery, visual fields and MRI at intervals determined by tumour size and response.
  • Ask patients and, with consent, close contacts about gambling, spending, hypersexuality, binge eating, sleep attacks and mood change during dopamine-agonist treatment.
  • For hypothalamic amenorrhoea, track observations, energy intake, exercise, psychological recovery, weight trajectory, injuries and menstruation without reducing recovery to a target weight alone.
  • Repeat DXA according to baseline deficit and ongoing risk, usually not more often than clinically useful, and assess calcium, vitamin D and fracture contributors.
  • Revisit contraception and conception plans because cabergoline or energy recovery can restore ovulation before predictable menses.

Special situations

Macroprolactin is an assay clue

Large prolactin-immunoglobulin complexes may elevate the reported result without equivalent biological activity, so laboratory fractionation can prevent unnecessary imaging.

The hook effect reverses intuition

An extremely high prolactin concentration can read falsely modest in a saturated assay, making a giant prolactinoma resemble stalk effect until dilution.

Fertility can precede bleeding

Ovulation may resume after cabergoline or energy recovery before the first visible period, creating an early pregnancy possibility.

BMI is not energy availability

A person at a conventional normal or high BMI can still have inadequate intake for training load and develop hypothalamic suppression.

A pill can hide non-recovery

Scheduled withdrawal bleeding on combined contraception can obscure whether endogenous GnRH and ovulation have recovered while nutritional bone injury continues.

Common pitfalls

  1. 01

    Diagnosing prolactinoma after one mildly high stressed sample without pregnancy, medicine, thyroid and macroprolactin review.

  2. 02

    Stopping an antipsychotic abruptly to lower prolactin without the prescribing mental-health team.

  3. 03

    Missing hook effect when a very large pituitary lesion has only a modest reported prolactin.

  4. 04

    Excluding functional hypothalamic amenorrhoea because BMI is not low.

  5. 05

    Prescribing combined contraception solely to treat bone loss and calling the withdrawal bleed recovery.

  6. 06

    Starting fertility induction before correcting severe energy deficit, cardiovascular instability and pregnancy risk.

After a reasonable nutritional, exercise and psychological trial, specialist transdermal oestradiol with cyclic progestogen may be considered for persistent hypo-oestrogenism; fertility induction occurs only after medical and energy recovery.
Heart rate below 40, systolic blood pressure below 90, marked orthostasis, hypothermia, electrolyte disturbance or recurrent syncope in suspected hypothalamic amenorrhoea supports inpatient medical evaluation.
  • A large sellar mass with only modest reported prolactin requires laboratory dilution to exclude the high-dose hook effect before classifying it as non-functioning.
  • Clear rhinorrhoea after rapid prolactinoma shrinkage can indicate a cerebrospinal-fluid leak and needs urgent skull-base assessment.
  • 05
    Medical-stability bloods and observations
    Why
    Detect complications of inadequate intake, purging, exercise or systemic disease in suspected hypothalamic amenorrhoea.
    Interpretation and limitations
    Bradycardia, hypotension, postural change, hypoglycaemia, electrolyte disturbance or organ dysfunction can require admission regardless of BMI.
  • 06
    Dual-energy X-ray absorptiometry
    Why
    Assess skeletal impact after six months of amenorrhoea or earlier when nutritional deficit or fracture raises concern.
    Interpretation and limitations
    Interpret age-appropriate Z-scores and fracture history, investigate other bone causes and track recovery rather than treating the scan alone.
    • 2
    Start the SmPC regimen low with food and titrate gradually to prolactin, symptoms, vision and imaging under the pituitary or fertility service.
  • 3Monitor for impulse-control change, somnolence, valvular or fibrotic symptoms and rapid-shrinkage CSF leak, with an individual pregnancy plan.
    • 03Suspected FHARestore energy and medical stabilityLow-oestrogen amenorrhoea occurs with restricted energy, exercise, stress or illness after key alternatives are excluded.+
    1. 1Assess pulse, blood pressure, orthostasis, temperature, glucose, electrolytes, intake, exercise, purging, stress, mood and fracture history, admitting instability.
    2. 2Use dietetic, psychological and medical support to increase energy intake, reduce excessive expenditure and treat an eating disorder or systemic disease.
    3. 3Follow menstrual, cardiovascular, nutritional and bone recovery without using a pill-induced withdrawal bleed as proof that the axis has recovered.
    04Persistent FHAProtect bone and plan fertilityAmenorrhoea and hypo-oestrogenism continue despite a reasonable multidisciplinary recovery trial.+
    1. 1Review whether energy availability and psychological drivers have genuinely improved and reassess for organic pituitary, ovarian or systemic disease.
    2. 2Consider specialist transdermal oestradiol with cyclic progestogen for ongoing deficiency, while continuing nutrition and exercise rehabilitation.
    3. 3For conception, complete fertility assessment and reach medical and energy stability before pulsatile GnRH or monitored gonadotrophin treatment.
    Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
    Lowers prolactin, restores gonadal function and shrinks most prolactinomas through long-acting dopamine D2 agonism.

    Cabergoline

    Start 0.5 mg orally per week in one or two doses with food; increase the total weekly dose gradually, usually by 0.5 mg at intervals of at least one month, to the lowest effective specialist dose.

    Review postural hypotension, nausea, sleepiness, impulse-control or psychiatric effects and fibrotic symptoms. For long-term treatment the SmPC contraindicates pre-existing valvulopathy and requires pre-treatment echocardiography; pregnancy and subsequent cardiac monitoring follow the specialist plan and product guidance.

    Supports bone and treats hypo-oestrogenic symptoms when functional hypothalamic amenorrhoea persists despite nutritional, exercise and psychological intervention.

    Transdermal oestradiol with cyclic progesterone

    After a recovery trial, the specialist may use a 17β-oestradiol patch in a physiological replacement dose with oral micronised progesterone 200 mg nightly for 12–14 days each 28-day cycle.

    This does not correct the energy deficit or provide reliable contraception; protect every intact uterus, investigate abnormal bleeding and individualise thrombotic, cancer and liver risk.