Introduction

Infections and drugs are the two leading causes of acute tubulointerstitial nephritis [2, 3]. Here, we report a well-documented case of acute eosinophilic tubulointerstitial nephritis likely caused by isotretinoin, a drug that is widely used to treat severe acne [5].

Case report

A 16-year old male patient on isotretinoin 40 mg/day (0.5 mg/kg/day) for 3 months because of acne was admitted to the emergency because of palpitations for some hours. On physical examination, body length was 1.80 m, weight 79.0 kg, heart rate 150/min, respiratory rate 25/min, blood pressure 110/65 mmHg, and axillary body temperature was 36.4°. Other physical examination findings were unremarkable. Increased creatinine (149 μmol/L; reference <133), urea (7.5 mmol/L; reference <7.1), and cystatin C (1.15 mg/L; reference <1.11) disclosed impaired kidney function. Hemoglobin (127 g/L), white blood cell count (11.4 × 109/L with 2.2 % eosinophils), platelet count (329 × 109/L), sodium (142 mmol/L), potassium (4.2 mmol/L), bicarbonate (24.9 mmol/L), potassium (4.2 mmol/L), glucose (5.1 mmol/L), alanine transaminase (9 U/L), and aspartate transaminase (16 U/L) were within normal values. Urinalysis findings were as follows: glucose +++, protein + (with an increased protein/creatinine of 291 mg/mmol, reference <30), 1–2 leukocytes on urine microscopy, and a negative urine culture. The tentative diagnosis of interstitial nephritis was confirmed by a renal biopsy (Fig. 1) showing a moderate interstitial inflammation with lymphocytes, plasma cells, and especially eosinophils as well as a mild interstitial fibrosis with tubular atrophy (but normal glomeruli). Hence, the diagnosis of eosinophilic, interstitial nephritis likely secondary to isotretinoin was made.

Fig. 1
figure 1

Histology showed interstitial inflammation with lymphocytes and eosinophils and interstitial fibrosis and tubular atrophy

Full size image

The vitamin A derivative was discontinued and a treatment with prednisolone 60 mg/day was given. Creatinine normalized within 6 days (79.5 μmol/L), and the drug management with prednisolone treatment pursued for a total of 3 months.

Discussion

Drugs are the most common cause of tubulointerstitial nephritis [2, 3]. Isotretinoin, which has been used since 1980s in the treatment of severe acne, has been so far associated with acute kidney injury in a 17-year old female and in a 16-year old male patient [1, 4]. Regrettably, the mentioned cases were not documented bio optically.

Isotretinoin is associated with a number of adverse effects that can be relevant and limit its use including teratogenicity; mucocutaneous side effects such as cheilitis, dry skin and mucous membranes, epistaxis, desquamation, photosensitivity, and pruritus; hypertriglyceridemia; and increased frequency of depression or suicide [5]. The present, well-document case report suggests that isotretinoin might also cause acute interstitial nephritis.