Endocrine Abstracts

Objectives: Factitious disorder imposed on self or Munchausen’s syndrome (MS), is a psychiatric disorder in which physical symptoms are intentionally produced without any practical benefit. Patients with MS represent a diagnostic dilemma as laboratory and clinical results can be inconsistent with the history and physical exam. The aim of this study was to evaluate the role of the levothyroxine overload test to differentiate MS from malabsorption and to treat life-threatening hypothyroidism.

Methods: 1 mg of levothyroxine was administered to patients referred to our Department for severe hypothyroidism and suspect malabsorption. TSH, FT4 and FT3 were measured at baseline, after 360 minutes and 2 to 7 days.

Results: we studied 9 hypothyroid patients (1 male and 8 females, mean age 46.2±14.8 years). Three female had Hashimoto’s thyroiditis while the remaining patients had undergone thyroidectomy for cancer (n = 5) or goiter (n = 1). Although at referral all patients had TSH >100 mU/l with low or even undetectable FT4/FT3, at the time of testing three of them had TSH 4.5, 23.6 and 39.1 mU/l, respectively. All patients adequately absorbed levothyroxine as shown in the table (data expressed as mean ±SD). The huge variability of results depended on the severity of their hypothyroidism, as we observed that the rate of change of FT4/FT3 was positively and that of TSH negatively correlated with baseline TSH levels (P <0.01; r²=0,69; 0,67 and 0,62), while did not correlate with patients’ weight or BMI. In patients with baseline TSH >200 mU/l, the TSH did not change significantly at 360 minutes, but declined few days after the overload (range 32-62%). In 5/9 patients additional levothyroxine loads were administered to achieve euthyroidism. None of the patients had adverse events or reported side effects. Three patients fulfilled the criteria for MS and were referred to a Psychiatrist. In 3 patients we suspected malingering, as they were asking for social assistance for disabled patients and were lost to follow-up after showing them the results of their testing. The remaining patients had an inadequate compliance or were taking levothyroxine with interfering drugs/foods; their thyroid function improved on follow up after proper instructions.

Conclusion: in patients with a severe hypothyroidism apparently unresponsive to treatment we suggest supervised levothyroxine administration before starting the workout for malabsorption. Subsequent overloads of levothyroxine might be given to rapidly achieve euthyroid.