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Health condition

MEN2, the RET mutation that shapes a whole family's care.

Multiple endocrine neoplasia type 2 is inherited, predictable, and manageable - if the right genetic testing and timing decisions happen early.

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Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against American Thyroid Association guidelines and specialist MEN clinic standards, referenced at the end.

  • 03

    Current for 2026

    Reflects modern genotype-phenotype risk stratification and selective RET inhibitor therapy for advanced disease.

Key facts

MEN2 at a glance.

The essentials, in plain English - what it is, the three subtypes, and how it's managed in the UK today.

  • What it is

    An inherited, autosomal dominant tumour syndrome caused by a mutation in the RET proto-oncogene.

  • Subtypes

    MEN2A, MEN2B and familial medullary thyroid carcinoma (FMTC) - each with a different tumour pattern and severity.

  • Nearly universal

    Medullary thyroid carcinoma (MTC) develops in virtually all mutation carriers, often before symptoms appear.

  • Inheritance

    Autosomal dominant - each child of an affected parent has a 1 in 2 chance of carrying the mutation.

  • Diagnosis

    Confirmed by RET genetic testing, which also predicts how aggressive the MTC is likely to be.

  • Key treatment

    Prophylactic thyroidectomy, timed by mutation risk category, prevents or removes MTC before it spreads.

Why this guide matters

One gene, three patterns, a whole family to consider.

MEN2 is unusual among cancer syndromes because we can often predict exactly what will happen, and when - if the genetics are read correctly.

  • Your mutation predicts your risk

    The specific RET change you carry tells your team how aggressive the medullary thyroid carcinoma is likely to be, and how soon to act.

  • Sequence of surgery matters

    A phaeochromocytoma is always excluded and treated before any thyroid or parathyroid operation - getting the order wrong is genuinely dangerous.

  • It runs in families

    A confirmed diagnosis is never just about one person - cascade testing lets relatives plan early, sometimes from infancy.

How the diagnosis is made

From suspicion to a genetically guided plan.

The steps a UK clinical genetics and endocrinology team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Suspicion from family history or a nodule

    A thyroid nodule, a phaeochromocytoma, or a family history of MEN2 prompts genetic assessment.

  2. 02

    Assessing

    RET mutation analysis

    The essential test - clinical genetics sequences the RET gene to confirm the diagnosis and identify the exact mutation.

  3. 03

    Assessing

    Risk category assigned

    The specific mutation places you in a highest, high or moderate risk group, which sets the timing of preventive surgery.

  4. 04

    Confirming

    Calcitonin and CEA measured

    Blood tumour markers track medullary thyroid carcinoma activity and help plan surgery timing.

  5. 05

    Confirming

    Phaeochromocytoma screening

    Plasma or urine metanephrines must be checked and any tumour treated before any other surgery is booked.

  6. 06

    Confirming

    Calcium and PTH checked (MEN2A)

    Screens for primary hyperparathyroidism, which affects around 20 to 30 percent of people with MEN2A.

  7. 07

    Preparing

    Thyroid ultrasound

    Images the thyroid for nodules or early medullary carcinoma before surgery is planned.

  8. 08

    Preparing

    Family cascade testing

    Once a mutation is confirmed, first-degree relatives are offered testing - starting in infancy where relevant.

Typical timeline: genetic confirmation in a few weeks, surgery timing planned over months to years by risk category.

Symptoms

What MEN2 actually looks like.

Signs vary by subtype and can appear years apart - or not at all before genetic screening finds them first.

  • Thyroid nodule or neck lump

    Often the first sign of medullary thyroid carcinoma, though it may be found on screening before any lump is felt.

  • Silent MTC on genetic screening

    Many people are diagnosed with early MTC through family screening, before any symptoms develop at all.

  • Paroxysmal high blood pressure

    Sudden surges in blood pressure with palpitations, headache and sweating suggest a phaeochromocytoma.

  • Palpitations and sweating episodes

    Classic phaeochromocytoma symptoms, often triggered by stress, exercise or certain foods.

  • Marfanoid body build (MEN2B)

    Tall, slender build with long limbs and lax joints - a distinctive feature of MEN2B.

  • Mucosal neuromas (MEN2B)

    Small, bumpy growths on the lips, tongue and inside the eyelids, often visible from early childhood.

  • Constipation or megacolon (MEN2B)

    Intestinal ganglioneuromatosis can cause chronic constipation, bloating and, rarely, a distended bowel.

  • Bone pain or kidney stones (MEN2A)

    Signs of hyperparathyroidism - raised calcium affecting bones, kidneys and mood.

Treatment

How MEN2 is managed in the UK.

Preventive surgery timed by genetics, careful surgical sequencing, lifelong surveillance, and targeted drugs for advanced disease.

  • Prophylactic thyroidectomy

    Timed by mutation risk category - within 6 months of life for the highest-risk MEN2B mutations, before age 5 for high-risk, or individualised for moderate-risk.

  • Laparoscopic adrenalectomy

    For phaeochromocytoma, after alpha-blockade preparation - always treated before any other planned surgery.

  • Parathyroidectomy

    For MEN2A-associated primary hyperparathyroidism, removing overactive parathyroid tissue as indicated.

  • Levothyroxine replacement

    Lifelong thyroid hormone replacement following thyroidectomy, dose-adjusted by regular blood tests.

  • Calcitonin and CEA surveillance

    Regular blood monitoring after thyroidectomy to detect residual or recurrent medullary thyroid carcinoma early.

  • Selective RET inhibitors

    Selpercatinib or pralsetinib for advanced or metastatic RET-altered MTC that cannot be fully controlled by surgery.

  • Genetic counselling

    Ongoing support for carriers and relatives, including cascade testing planned from infancy in at-risk families.

  • MDT specialist care

    Endocrinology, endocrine surgery, clinical genetics and specialist MEN clinics working together, often with AMEND patient support.

What this guide is based on

The sources behind every claim on this page.

American Thyroid Association guidance, UK specialist MEN clinic standards and patient charity information, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your clinical genetics team or endocrinologist knows your mutation and history and can tell you which parts apply to you. If in doubt, get seen.

  • American Thyroid Association (ATA). Management guidelines for medullary thyroid carcinoma.

  • AMEND (Association for Multiple Endocrine Neoplasia Disorders). Patient information on MEN2.

  • UK specialist MEN clinics and clinical genetics services - commissioned guidance on RET testing and surveillance.

  • MHRA and specialist oncology guidance on selective RET inhibitors for advanced medullary thyroid carcinoma.

Red flags

When MEN2 needs urgent attention.

Most care is planned and scheduled. These are the situations that aren't - and where a specialist opinion is needed without delay.

  • Undiagnosed phaeochromocytoma before surgery

    Operating on the thyroid or parathyroid before excluding a phaeochromocytoma risks a hypertensive crisis under anaesthesia - always screen first.

  • MEN2B in infancy

    The most aggressive MTC risk category - prophylactic thyroidectomy is recommended within the first 6 months of life.

  • Rapidly rising calcitonin

    A steep rise suggests progressing or recurrent medullary thyroid carcinoma and needs prompt specialist review.

  • Metastatic MTC

    Spread beyond the neck warrants discussion of selective RET inhibitor therapy at a specialist MEN or thyroid cancer centre.

  • Untested at-risk relatives

    A confirmed RET mutation in the family means relatives should be offered genetic counselling and testing without delay.

  • Severe constipation in MEN2B

    Intestinal ganglioneuromatosis can progress to megacolon - persistent symptoms need gastroenterology input.

  • New hypertension in a known carrier

    Any new or worsening high blood pressure in someone with MEN2 should prompt phaeochromocytoma screening.

Living with it

A predictable condition, with a clear timeline.

Four things that make the biggest difference over the years - understanding your own mutation, respecting the order of surgery, staying on top of monitoring, and thinking of your family too.

A quiet reminder

Knowing your risk category changes everything.

MEN2 rewards early, informed decisions - ask your team to explain exactly what your mutation means for you and your children.

  1. 01 Timing

    Surgery timing is personal

    Your specific RET mutation, not a generic rule, decides when prophylactic thyroidectomy makes sense - ask your team to explain your category.

  2. 02 Sequence

    Phaeochromocytoma first, always

    If you have both a phaeochromocytoma and a thyroid or parathyroid problem, the adrenal tumour is treated first for anaesthetic safety.

  3. 03 Monitor

    Lifelong surveillance matters

    Regular calcitonin, CEA and calcium checks catch recurrence or new tumours early, when they are easiest to treat.

  4. 04 Family

    Think beyond yourself

    A confirmed diagnosis affects your children and siblings too - genetic counselling helps the whole family plan calmly.

Frequently asked

Everything we get asked about MEN2.

Quick answers on genetic testing, subtypes, surgery timing and treatment for advanced disease.

  • What is multiple endocrine neoplasia type 2 (MEN2)?

    MEN2 is an inherited condition caused by a mutation in the RET gene that predisposes carriers to medullary thyroid carcinoma and, depending on the subtype, phaeochromocytoma and other endocrine tumours. It is autosomal dominant, meaning each child of an affected parent has a 1 in 2 chance of inheriting it.

  • What is the difference between MEN2A, MEN2B and FMTC?

    MEN2A causes medullary thyroid carcinoma in almost everyone, phaeochromocytoma in about half, and hyperparathyroidism in around a fifth to a third. MEN2B causes an earlier and more aggressive medullary thyroid carcinoma plus phaeochromocytoma, a marfanoid build and mucosal neuromas, but not hyperparathyroidism. FMTC causes medullary thyroid carcinoma alone and is generally the mildest form.

  • Why is genetic testing so important in MEN2?

    RET mutation analysis confirms the diagnosis, places you in a risk category that predicts how aggressive the medullary thyroid carcinoma is likely to be, and guides exactly when prophylactic thyroidectomy should happen. It also allows relatives to be tested through cascade screening.

  • Why must a phaeochromocytoma be excluded before thyroid surgery?

    An undiagnosed phaeochromocytoma can cause a dangerous surge in blood pressure under anaesthesia. Plasma or urine metanephrines are checked and any phaeochromocytoma is treated with alpha-blockade and surgery before any other operation goes ahead.

  • When is prophylactic thyroidectomy recommended?

    Timing follows the specific RET mutation risk category. The highest-risk MEN2B mutations call for surgery within the first 6 months of life, high-risk mutations before age 5, and moderate-risk mutations are timed individually based on calcitonin levels and family preference.

  • What if medullary thyroid carcinoma has already spread?

    For advanced or metastatic RET-altered disease that surgery cannot fully control, selective RET inhibitors such as selpercatinib or pralsetinib are available through specialist oncology services, alongside ongoing MDT care.

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