Hypothyroidism presenting as a polymyositis‐like syndrome. Report of two cases

Abstract

Two patients with proximal muscle weakness and marked elevations of serum muscle enzymes were initially believed to have polymyositis; however electromyography and muscle biopsies were normal. Both patients were subsequently found to have hypothyroidism. Each regained her muscle strength, and serum enzymes normalized with thyroid hormone replacement. Because muscle weakness and an elevated creatine phosphokinase occur in most patients with hypothyroidism, thyroid dysfunction must be considered in the differential diagnosis of polymyositis.Polymyositis is characterized clinically by symmetric proximal muscle weakness and, less frequently, by muscle pain and tenderness. Chemically, the levels of Submitted for publication February 10, 1976: accepted April 19, 1976 serum enzymes concentrated in skeletal muscle are almost invariably elevated. It is not well appreciated that hypothyroidism can present as a muscular syndrome indistinguishable both clinically and chemically from polymyositis, with few of the stigmata usually associated with thyroid hormone deficiency.It is the purpose of this report to describe 2 patients initially believed to have polymyositis on the basis of severe proximal myopathy with profound serum muscle enzyme elevations. Both were subsequently found to have primary hypothyroidism. The discriminating clinical and laboratory features are discussed, and the muscular abnormalities associated with hypothyroidism are reviewed. CASE REPORTS Patient 1RL, a 34-year-old Latin American housewife, was admitted to The Wilford Hall USAF Medical Center for evaluation of progressive proximal limb-girdle muscle pain and weakness of 4 months duration. Past health had been good, except for depressive symptoms of 3 years duration. In addition to muscular pain and weakness, she complained of paresthesias of the first four fingers of both hands and of periorbital swelling not associated with skin rash. There was no history of articular pain or of swelling, alopecia, or sicca symptoms.Physical examination disclosed an obese, chronically ill appearing white female. The pulse was 68/minute, blood pressure 110/60 mm Hg. and temperature normal. The skin revealed periungual erythema, and the hair was fine and dry. The thyroid gland was neither enlarged nor nodular. All

Hypothyroidism masquerading as polymyositis

“…There is a well-known association between hypothyroidism and muscle disease, ranging from asymptomatic elevation of serum muscle enzymes to severe clinical muscle disease (Astrom et al, 1961;Comings, 1962;Norris and Panner, 1966;Fessel, 1968;Goldberg, 1970;Ramsay, 1974;Ingbar and Woeber, 1974;Hochberg et al, 1976;Klein et al, 1981). Muscle weakness of the shoulder and the pelvic girdles is often found in hypothyroidism.…”

“…Rarely, however, the myopathy is severe and might be the presenting symptom (Hochberg et al, 1976). Such cases can be misdiagnosed and mistreated as polymyositis.…”

Pattern of Adult Onset of Polymyositis and Dermatomyositis and Association with Malignancy

“…One patient with RA and concomitant hypothyroidism presenting with muscle weakness and raised muscle enzyme [13] and 11 patients with childhood onset (before age 16) were excluded. The remaining 22 patients fulfilled the proposed criteria for diagnosis of PM/DM (symmetrical muscle reactive, raised muscle enzymes, positive muscle biopsy, electromyographic abnormality consistent with myositis and dermatologie features).…”

Role of Thyroid Disease in the Development of Statin-Induced Myopathy

“…6,9 It is well recognized that hypothyroid patients can first manifest their disease with pain, stiffness, cramps, and symmetric proximal muscle fatigability, most commonly of the shoulder and pelvic girdles, and marked serum CK elevation that clinically resembles polymyositis. 12 Coexisting clinical signs and symptoms of hypothyroidism, including delayed relaxation phase of the deep tendon reflexes, a normal electromyogram, and the absence of the characteristic inflammatory changes on muscle biopsy, all help to distinguish hypothyroid myopathy from polymyositis. 10,[12][13][14][15][16][17][18] Electromyographic studies in such patients have yielded normal results in many of the patients and neuromyopathic changes consistent with "nonspecific hypothyroid myopathy" in the others.…”

“…12 Coexisting clinical signs and symptoms of hypothyroidism, including delayed relaxation phase of the deep tendon reflexes, a normal electromyogram, and the absence of the characteristic inflammatory changes on muscle biopsy, all help to distinguish hypothyroid myopathy from polymyositis. 10,[12][13][14][15][16][17][18] Electromyographic studies in such patients have yielded normal results in many of the patients and neuromyopathic changes consistent with "nonspecific hypothyroid myopathy" in the others. 6,11,15,19,20 Muscle biopsies were normal in 25% of patients observed, whereas the remaining biopsies have demonstrated varying degrees of type II fiber atrophy, type I fiber hypertrophy, central nuclei deposition, and increased percentage of type I fibers.…”