Abstract
Intermittent hyperthyreosis occurs under various forms of stress, especially heat
stress. The clinician may diagnose such cases as masked or apathetic hyperthyroidism
or "formefruste" hyperthyreosis or thyroid autonomy. As most routine and standard
tests may here yield inconsistent results, it is the patients' anamnesis which may
provide the clue. Our Bioclimatology Unit has now seen over 100 cases in which thyroid
hypersensitivity towards heat was the most prominent syndrome: 10-15% of weather-sensitive
patients are affected. The patients complain before or during heat spells of such
contradictory symptoms as insomnia, irritability, tension, tachycardia, palpitations,
precordial pain, dyspnoe, flushes with sweating or chills, tremor, abdominal pain
or diarrhea, polyuria or pollakisuria, weight loss in spite of ravenous appetite,
fatigue, exhaustion, depression, adynamia, lack of concentration and confusion. Determination
of urinary neurohormones allows a differential diagnosis, intermittent hyperthyreosis
being characterized by three cardinal symptoms:
1. tachycardia - every case with more than 80 pulse beats being suspect (not specific);
2. urinary histamine - every case excreting more than 90 µg/day being suspect. Again
the drawback of this test is its lack of specificity, as histamine may also be increased
in cases of allergy and spondylitis;
3. urinary thyroxine - every case excreting more than 20 µg/day T-4 being suspect.
This is the only specific test.
Therapy should make use of lithium carbonate and beta-blockers. Propyl thiouracil
is rarely required.
Key words
Apathetic Hyperthyroidism - Forme Fruste - Histamine - Hyperthyreosis - Hyperthyroidism
- Intermittent Hyperthyreosis - Masked Hyperthyroidism - Thyroid Autonomy
1 Supported by a grant from the Joint Research Fund of the Hebrew University and Hadassah,
Jerusalem.
