Evaluation of two over-the-counter natural thyroid hormone preparations in human volunteers.
OBJECTIVE
To determine the pharmacologic activity of over-the-counter (OTC) thyroid preparations.


METHODS
In vitro analysis and a prospective, crossover study in vivo.


METHODS
Tertiary care center.


METHODS
Two healthy adult volunteers.


METHODS
Three OTC preparations (Thyrotrophin PMG [bovine thyroid PMG extract], Thyro Forte [thyroid lymphogland concentrate with synergistic complex], and Thyro Complex [thyroid lyophilized gland concentrate with synergistic complex]) were analyzed in vitro. Volunteers were administered two times the manufacturer's maximum recommended daily dose of either Thyrotrophin PMG or Thyro Forte for one week, washed out for four to five weeks, and crossed over to receive the opposite tablet preparation for an additional week.


METHODS
The triiodothyronine (T3) and thyroxine (T4) contents of OTC preparations were measured by HPLC. Vital signs, serum total and free T4, total T3, thyroid stimulating hormone, thyroxine binding globulin, thyroglobulin, and general chemistry tests (including glucose and cholesterol) were monitored before, during, and between administration of the products.


RESULTS
HPLC analysis of the three OTC preparations showed no T4 but did show possible T3 in two of these products. We found no definite clinical or laboratory evidence of thyroid hormone excess with either product.


CONCLUSIONS
Healthcare professionals should advise against the use of these scientifically unsound and relatively expensive OTC thyroid preparations, of which the therapeutic efficacy is unknown.
Csako
G
G
Clinical Pathology Department, National Institutes of Health, Bethesda, MD 20892.
Corso
D M
DM
Kestner
J
J
Bokser
A D
AD
Kennedy
P E
PE
Pucino
F
F
D004341:Drug Evaluation; D006801:Humans; D004366:Nonprescription Drugs; D013607:Tablets; D013954:Thyroglobulin / Q000097:blood; D013963:Thyroid Hormones / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000032:analysis; D013975:Thyroxine-Binding Proteins / Q000032:analysis; D014284:Triiodothyronine / Q000032:analysis
D004366:Nonprescription Drugs; D013607:Tablets; D013963:Thyroid Hormones; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine