Abstract
Objective:
To determine why patients with normal function of the pituitary-thyroid axis, myofascial pain, and other symptoms resembling those of hypothyroidism respond to a slightly supraphysiological dose of levothyroxin administration.
Design:
Review and analysis of author’s records drawn from a data base of therapeutic trials.
Intervention:
Oral administration of levothyroxin, 0.2 mg daily for at least 3 months.
Main Outcome Measures:
Patient interviews and physical examinations by author. Measurement of differences in paired BMR, serum cholesterol, and subjective response after 3 or more months of thyroid hormone administration, using each patient as his or her own control.
Summary:
Fifty-seven chemically euthyroid adults of both sexes with myofascial pain and hypothyroid-like symptoms were treated with a slightly supraphysiological dose, 0.2 mg, of levothyroxin daily. Cases were selected recently from a database of 367 therapeutic trials performed by the author between 1954 and 1983. All patients had a normal thyroid profile, and a serum TSH measurement before initiating levothyroxin replacement. BMRs and serum cholesterol determinations before and after at least 3 months of thyroid hormone therapy were compared. A graph was constructed in which each point displayed three responses for each patient: change in resting oxygen consumption, following a 12-h fast (BMR); change in serum cholesterol; and symptom response score. Thirteen TSH levels were slightly elevated. Analysis of the graph suggests that almost all patients with: (1) normal function of the pituitary thyroid axis; (2) non-inflammatory myofascial pain refractory to physical medicine and trigger point therapy; and (3) symptoms and signs resembling hypothyroidism, responded to thyroid hormone therapy. The responses suggest correction of a peripheral block to thyroid hormone in patients with normal pituitary thyrotroph function.
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