Endocrine and Hormone Late Effects

NCI lists the endocrine system among the body systems that can be harmed years after cancer treatment. Damage to the thyroid, the ovaries and the testes can cause early menopause, infertility, an underactive thyroid, an overactive thyroid, and weight gain.

Here is the pattern worth holding on to. Hormone problems arrive slowly, and their symptoms are ordinary. Tiredness. Feeling cold. Weight change. Low mood. Loss of interest in sex. None of that looks like an emergency. Most people file it under stress or age. That is exactly why these problems get missed for years.

The fix is not vague vigilance. It is knowing which gland your own treatment put at risk, and asking for the matching blood test by name.

An underactive thyroid, called hypothyroidism, is one of the more common late effects. The gland stops making enough thyroid hormone.

Early signs are fatigue, feeling cold, constipation, weight gain, dry skin, and depression. Later signs include a puffy face, hands and feet, a slow heart rate, and a low body temperature.

Two blood tests find it. One is free thyroxine, written free T4. The other is thyroid stimulating hormone, or TSH. TSH comes from the pituitary gland and tells the thyroid what to do.

Treatment is levothyroxine, a daily tablet. MedlinePlus notes that most people with an underactive thyroid need it for life.

An overactive thyroid can also follow treatment. NCI lists both the underactive and the overactive form as late effects.

There is a rare emergency form of severe hypothyroidism called myxedema coma. Signs include a below-normal body temperature, slowed breathing, low blood pressure, and being unresponsive. It needs immediate hospital care.

The pituitary is a small gland at the base of the brain. It directs several other glands. Hypopituitarism means it no longer makes normal amounts of some or all of its hormones.

MedlinePlus lists radiation therapy to the brain, brain surgery, brain tumor and head trauma among the causes. If your treatment included any of those, read this section closely.

Each missing hormone gives its own picture.

• ACTH loss lowers cortisol. That brings low blood pressure and low blood sugar.
• TSH loss causes thyroid problems that slow the body down.
• LH and FSH loss causes lack of sex drive, infertility, and irregular menstrual periods.
• Growth hormone loss causes short height and slowed growth in children.
• Prolactin loss causes failure to release milk after a birth.
• ADH loss causes heavy urination and constant thirst.

Treatment is lifelong hormone replacement. That may include corticosteroids, growth hormone, sex hormones, thyroid hormone, and desmopressin.

MedlinePlus gives one instruction that is easy to act on this week. Always carry a medical ID saying you have adrenal insufficiency.

Adrenal insufficiency means the body has too little cortisol. It can start in the adrenal glands themselves. It can also start in a pituitary that no longer sends the ACTH signal.

Two routes matter most after cancer treatment.

• Long-term steroid treatment that is then stopped suddenly. MedlinePlus names this directly as a cause of adrenal crisis: "You've been taking glucocorticoid medicines for a long time, and suddenly stop."
• Damage to the pituitary from brain radiation or brain surgery.

The slow-building signs, from the MedlinePlus page on Addison disease, are abdominal pain, ongoing digestive problems, darkening of the skin, dizziness, low blood pressure, extreme weakness and fatigue, weight loss with poor appetite, salt cravings, low blood sugar, and fever.

Testing includes blood cortisol, sodium and potassium. A cosyntropin (ACTH) stimulation test may be added.

MedlinePlus is blunt about the treatment. "Never skip doses of your medicine for this condition because life-threatening reactions may occur."

MedlinePlus says this plainly. "Go to the emergency room or call the local emergency number (such as 911) if you develop symptoms of acute adrenal crisis."

Those symptoms are:

• Abdominal pain or flank pain.
• Confusion, loss of consciousness, or coma.
• Dehydration.
• Dizziness or lightheadedness.
• Fatigue, severe weakness.
• Headache.
• High fever.
• Loss of appetite.
• Low blood pressure.
• Low blood sugar.
• Nausea and vomiting.
• Rapid heart rate.
• Rapid breathing.
• Slow, sluggish movement.
• Unusual and heavy sweating on the face or palms.

An infection or other physical stress can set this off. Treatment is hydrocortisone given straight into a vein or a muscle. Fluids go in through a vein if blood pressure is low. This is not something to ride out at home.

NCI lists damage to the ovaries and testes as a late effect. It can cause early menopause and infertility.

When the pituitary stops making LH and FSH, the result is loss of sex drive, infertility, and irregular periods.

Be specific at the visit. "My periods stopped eight months ago and I am 31" gets a different answer than "I am tired."

Growth hormone loss causes short height and slowed growth in children. Growth is measurable, so it is often the earliest hormone signal a family can see.

Keep the growth chart going after treatment ends. Bring the actual numbers to appointments. A single height at one visit tells nobody very much. A line over three years tells them a lot.

NCI's childhood late-effects summary makes a link that surprises people. Lower-than-normal amounts of thyroid, growth, or sex hormones count as a risk factor for heart and blood vessel problems.

So an untreated hormone deficiency is not only a hormone problem. That is a reason to fix it, not to live with it.

Do not ask whether you should "get your hormones checked." Ask for the test that matches what you were treated with.

• Radiation near the neck or thyroid: ask for TSH and free T4.
• Radiation to the brain, brain surgery, or a pituitary tumor: ask which pituitary hormones need checking, and how often.
• Long-term steroids, or steroids stopped recently: ask whether you need adrenal testing, and what to do when you get sick.
• Periods stopped, or sex drive dropped: ask which sex hormone levels apply, and whether a fertility referral is still worth making.
• A child or teen still growing: ask for growth and puberty tracking on a chart, not just a comment in the notes.

Thyroid replacement, steroid replacement and sex hormone replacement are not optional and not adjustable at home. Stopping steroid replacement can trigger adrenal crisis.

If the problem is cost, side effects, or the number of pills, say so out loud. Those are fixable through the prescriber. Quietly stopping is not.

• Late Effects of Cancer Treatment — National Cancer Institute
• Late Effects of Treatment for Childhood Cancer (PDQ), Patient Version — National Cancer Institute
• Hypopituitarism — MedlinePlus Medical Encyclopedia
• Acute adrenal crisis — MedlinePlus Medical Encyclopedia
• Addison disease — MedlinePlus Medical Encyclopedia
• Hypothyroidism — MedlinePlus Medical Encyclopedia