LETTER
Thyrotoxicosis Insistiates: Report of 17 Cases
Steven Snyder, MD, and
Marc Jaffe, MD
1 July 1997 | Volume 127 Issue 1 | Page 88
TO THE EDITOR:
Although thyrotoxicosis secondary to the ingestion of excess thyroid hormone (thyrotoxicosis medicamentosa or thyrotoxicosis factitia) has been well documented [1], no previous reports have described patients who insist that their physician prescribe thyroid hormone replacement therapy (THRT) that results in consistently undetectable serum thyroid-stimulating hormone (TSH) levels (sensitivity of assay, 0.002 µU/mL).
We have found 17 patients with thyrotoxicosis insistiates (Latin for "thyrotoxicosis having been demanded or insisted") followed by endocrinologists in our large health maintenance organization. Most of the patients began receiving THRT by fee-for-service physicians in the early 1970s before joining our health maintenance organization. All of these patients insist that their symptoms of fatigue or depression or their weights (or both) should govern the dosage of THRT (L-thyroxine dosage ranged from 175 to 700 micro g/d for 13 patients, and thyroid extract dose ranged from 3 to 7 grains for 4 patients) and that consistently undetectable serum TSH levels should be ignored, even in the face of osteoporosis or atrial tachyarrhythmia. Any physician who attempts to modify the dosage of THRT is summarily dismissed by the patient.
One previous study suggested that patients feel better while receiving a daily dosage of L-thyroxine that is 50 micro g/d greater than the optimal dosage suggested by the serum TSH level [2]. Other studies report that THRT has been used to supplement the treatment of depression [3, 4]. The insistence that the serum TSH level should be the ultimate determinant of tissue thyroid hormone needs could be questioned because the pituitary gland may derive more triiodothyronine from thyroxine than do peripheral tissues [5]. We assume, however, that patients with thyrotoxicosis insistiates have an underlying psychiatric disorder or a fixation on THRT that cannot be broken.
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Author and Article Information
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Kaiser Permanente Medical Center; South San Francisco, CA 94080
1. Cohen JH III, Ingbar SH, Braverman LE. Thyrotoxicosis due to ingestion of excess thyroid hormone. Endocrinol Rev. 1989; 10:1133-24.
2. Carr D, McLeod DT, Parry G, Thornes HM. Fine adjustment of thyroxine replacement dosage: comparison of the thyrotrophin releasing hormone test using a sensitive thyrotrophin assay with measurement of free thyroid hormone and clinical assessment. Clin Endocrinol (Oxf). 1988; 28:325-33.
3. Goodwin FK, Prange AJ Jr. Potentiation of antidepressant effects by L-triidothyronine in tricyclic nonresponders. Am J Psychiatr. 1982; 139:34-8.
4. Gupta S, Masand P, Tanquary JF. Thyroid hormone supplementation of fluoxetine in the treatment of major depression. Br J Psychiatr. 1991; 159:866-7.
5. Larsen RP. Thyroid pituitary interaction: feedback regulation of thyrotrophin secretion by thyroid hormones. N Engl J Med. 1982; 306:23-32.
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