Accuracy of physical examination in the diagnosis of hypothyroidism: a cross-sectional, double-blind study.

BACKGROUND Hypothyroidism is a common, potentially treatable endocrine disorder. Since hypothyroidism is not always associated with the signs and symptoms typically attributed to it, the diagnosis is often missed. Conversely, patients with typical signs and symptoms may not have the disease when laboratory tests are performed. AIMS We aimed to determine the accuracy of physical examination in the diagnosis of hypothyroidism. SETTING AND DESIGN Prospective, hospital-based, cross-sectional diagnostic study. MATERIAL AND METHODS Consecutive outpatients from the medicine department were screened and an independent comparison of physical signs (coarse skin, puffy face, slow movements, bradycardia, pretibial oedema and ankle reflex) against thyroid hormone assay (TSH and FT4) was performed. STATISTICAL ANALYSIS Diagnostic accuracy was measured as sensitivity, specificity, positive likelihood ratios, negative likelihood ratios and positive and negative predictive values. RESULTS Of the 1450 patients screened, 130 patients (102 women and 28 men) underwent both clinical examination and thyroid function tests. Twenty-three patients (18%) were diagnosed to have hypothyroidism by thyroid hormone assays. No single sign could easily discriminate a euthyroid from a hypothyroid patient (range of positive likelihood ratio (LR+) 1.0 to 3.88; range of negative likelihood ratio (LR-): 0.42 to 1.0). No physical sign generated a likelihood ratio large enough to increase the post-test probability significantly. The combination of signs that had the highest likelihood ratios (coarse skin, bradycardia and delayed ankle reflex) was associated with modest accuracy (LR+ 3.75; LR- 0.48). CONCLUSION Clinicians cannot rely exclusively on physical examination to confirm or rule out hypothyroidism. Patients with suspected hypothyroidism require a diagnostic workup that includes thyroid hormone assays.