Rapid progression from subclinical to symptomatic overt hypothyroidism.
OBJECTIVE
To report a case of Hashimoto's thyroiditis with rapid progression from subclinical to overt symptomatic hypothyroidism and to discuss the potential precipitating factors and the implications on clinical decisions about monitoring and treatment of early thyroid failure.


METHODS
We describe a patient with long-standing subclinical hypothyroidism who had progression to severe overt hypothyroidism during a 2-month period, without an identifiable precipitating factor. All medical care was provided at a single institution, and all relevant medical records were reviewed.


RESULTS
For at least 2 years, an 84-year-old man had a pattern of subclinical hypothyroidism, including normal levels of serum free thyroxine, serum thyrotropin concentrations ranging from 4.4 to 9.6 microIU/mL, and elevated levels of anti-thyroid peroxidase antibodies. During a 2-month period, symptoms of cold intolerance, a 4.5-kg weight gain, and fatigue developed, and the patient was found to have low free thyroxine and free triiodothyronine concentrations and a serum thyrotropin concentration of 80.9 microIU/mL. The patient did not use any medication previously identified as a trigger to the development of hypothyroidism, had no exposure to iodine or contrast administration, and reported no intercurrent infection that might explain the rapid progression of hypothyroidism.


CONCLUSIONS
Most patients with subclinical hypothyroidism have progression to overt hypothyroidism at a slow rate. Elderly patients with high antithyroid antibody titers may have a higher than previously recognized risk of rapid development of overt hypothyroidism, and earlier intervention with levothyroxine treatment may be indicated.
Heymann
Robert
R
Endocrinology and Diabetes Division, VA Greater Los Angeles Healthcare System, David Geffen School of Medicine at UCLA, California 90073, USA.
Brent
Gregory A
GA
D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D009994:Osmolar Concentration; D012720:Severity of Illness Index; D013967:Thyroiditis, Autoimmune / Q000150:complications*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine