Resolution of nephrotic syndrome caused by amyloidosis following surgery for Crohn's disease
Authors: Leiper K , Howse MLP , Bell GM 
Published: May 2014

A16-year-old apprentice electrician was referred with nephrotic syndrome. He had a 3-month history of swelling of the ankles, eyelids and face. Asthma had been diagnosed at the age of 11 years and had been treated with inhaled salbutamol and beclomethasone. As a young child he had also required intermittent courses of oral prednisolone. In his mid teens he had been referred to his local paediatrician for investigation of short stature. Between the ages of 11 and 15 years his height and weight had fallen from the 92nd to the 12th and from the 85th to the 3rd centiles respectively. After investigation the growth retardation was attributed to his oral steroid use.

On examination he appeared well. Secondary sexual characteristics were absent, blood pressure was 100/70 mmHg, there was moderate ankle and periorbital oedema. No other abnormalities were detected. Investigations were as follows: 12.3g urinary protein/24 hours, serum creatinine 95 mmol/litre, creatinine clearance 64 ml/min, serum cholesterol 7 mmol/litre, erythrocyte sedimentation rate 90 mm/hr, haemoglobin, 11.3 g/litre and mean corpuscle volume 69 fl. Tests for thyroid function, ferritin and iron studies, blood sugar, C-reactive protein, immunoglobulins and serum electrophoresis, complement levels, antinuclear antibody, extractable nuclear antigen antibodies, antineutrophil cytoplasmic antibodies and antiglomerular basement antibody were all normal or negative. The proteinuria was shown to be highly selective and he was treated empirically with prednisolone 40 mg daily, ranitidine 150 mg twice daily and frusemide 40 mg daily.

His nephrotic syndrome proved refractory to treatment and he was admitted with worsening leg oedema. The diuretic dosage was increased and with informed consent a percutaneous renal biopsy was performed. This showed glomerular deposition of structureless eosinophilic material in the mesangium that extended into the glomerular basement membrane. The material stained positive for amyloid by Congo red. Electron microscopy confirmed the presence of typical amyloid fibrils in the glomeruli, vessels and around the tubules. Histopathologically it was impossible to determine whether this was primary or secondary amyloidosis.

A search for causes of secondary amyloidosis was undertaken. In view of the history of asthma a salt sweat test and chest computed tomography were performed. These showed no evidence of cystic fibrosis or bronchiectasis respectively. Belatedly the patient mentioned that he had longstanding but intermittent central abdominal discomfort which he had always considered to be ‘normal’. He had, however, noticed that it had improved while he was on steroid treatment. A subsequent barium meal and follow-through showed a tight elongated stricture of the terminal ileum of approximately 10–20 cm.

The patient was referred for right hemicolectomy. Preoperatively he was shown to have abnormal short and long synacten tests but the operation proceeded with hydrocortisone cover.

Two macroscopically typical lesions of Crohn's disease measuring 2 and 15 cm were found affecting the terminal ileum. The other abdominal organs and pelvis were normal. A routine right hemicolectomy was performed. The patient recovered from the operation uneventfully.

Histological examination of the terminal ileum showed a chronic transmural infiltrate with granulomata. The mucosa was ulcerated and fissured. Amyloid deposition was noted in the submucosal vessels (Figure 1).

His immediate postoperative course was uncomplicated. Over the following months and years his ankle oedema disappeared and he achieved sexual maturity. The proteinuria fell and when last measured, 4.5 years after the procedure, was 0.8g/24 hours (Figure 2). The serum albumin also rose to the normal range. His hydrocortisone was discontinued in 1995 following which a repeat short synacthen test was normal. Creatinine clearance rose to 110 ml/min. A repeat renal biopsy was considered to be unnecessary.