Hyponatremia in a child with Takayasu arteritis: Questions

Abstract

A 12-year-old boy was referred to us with a 3-year history of recurrent fever and joint pains. Four months previously, the child had been admitted for generalized tonic–clonic convulsions, for which a computed tomography (CT) scan of the brain had been performed and reported to be normal. There was no recurrence of seizures, but the parents noticed that the child was losing weight, was very thirsty, and was passing large volumes of urine. Complaints of headache and diplopia during the preceding 10 days led to re-admission to hospital. However, the child developed progressive breathlessness and was therefore referred to us for further management. On examination, the child was conscious, irritable, and very thirsty. The respiratory rate was 70/min, pulse was 184/ min, and blood pressure was 160/130 mmHg in the left upper limb, 154/130 mmHg in the right upper limb, 146/ 126 in the right lower limb, and 148/128 in the left lower limb. All peripheral pulses were palpable. His weight and height were 28 kg and 126 cm, respectively, both below the 5th percentile for age and sex. The skin showed no cafe-aulait spots. There was no significant lymphadenopathy. On examination of the cardiovascular system, the jugular venous pressure was 7 cm above the sternal angle. The apical impulse was in the sixth left intercostal space lateral to the mid-clavicular line, and there was a gallop rhythm. Respiratory system examination revealed bilateral basal crepitations. The liver was tender and palpable 5 cm below the right costal margin. There was no abdominal bruit. The fundus showed disc edema, cotton wool exudates, focal hemorrhages, and arterio-venous nicking. Other organ systems were essentially normal. Further tests revealed a hemoglobin of 9.8 g/dl, total white blood cell count of 11,000/mm with a differential count of polymorphs of 68 %, lymphocytes of 30 %, and monocytes of 2 %, and platelet count of 1,86,000/mm. The erythrocyte sedimentation rate was 75 mm at the end of 1 h. Urinanalysis showedmicroscopic hematuria and 3+ proteinuria. Serum and urine electrolyte values are given in Table 1. Serum creatinine was 0.7 mg/dL. The Mantoux test showed no induration at 48 h. Chest X-ray showed cardiomegaly with a cardiothoracic ratio of 0.7 and features suggestive of pulmonary edema. Abdominal ultrasonography revealed a small atrophic right kidney (6.2×2.3 cm) with decreased vascularity within and compensatory hypertrophy of the left kidney (11.1×5.2 cm). Renal Doppler showed a poor flow in the right intra-renal arteries with poor visualization of the R renal ostium. The left kidney showed hypertrophy, and the entire left renal artery was prominent with increased flow within. Two-dimensional echocardiography showed concentric hypertrophy of the left The answers to these questions can be found at http://dx.doi.org/10.1007/ s00467-012-2189-6.