Case Report: A rare renal manifestation of Acute intermittent porphyria

Introduction

Acute porphyria is a group of rare metabolic disorders characterized by enzyme deficiencies in heme biosynthesis.^1,2 Acute porphyria primarily affects the nervous system and renal involvement is uncommon. Porphyrins are highly reactive to ultraviolet rays; in urine, they turn a reddish hue upon exposure to sunlight.³ There are various causes of renal failure in acute porphyria with acute interstitial nephritis (AIN), an infrequent manifestation characterized by interstitial inflammation and tubular injury. To our knowledge, this is the first case report of acute tubulointerstitial nephritis secondary to acute intermittent porphyria in India.

Case

A 21-year-old female born to non-consanguineous parents presented with complaints of abdominal pain and altered sensorium. She had hypertension at presentation, neck stiffness, and a fundus within normal limits. All other systemic examination results were normal. Laboratory tests (Table 1) revealed normocytic normochromic anemia with deranged renal function tests and bland urine. Sepsis markers were standard, and the cultures were sterile. The ultrasonography results were within normal limits. ECG, 2 D Echo, and neuroimaging were performed, which was expected. Urine color provided a clue to evaluate the lines of porphyria, leading to the diagnosis of acute porphyria. Treatment included glucose administration and other supportive measures to improve the patient’s overall clinical condition. No nephrotoxic agents were used before admission, during the hospital stay, or after discharge from the hospital. She had persistent renal dysfunction for approximately six weeks following her acute episode. Hence, renal biopsy was done which revealed acute tubulointerstitial nephritis with early tubular chronicity (Figure 1 and Figure 2). She received oral steroids (0.5 mg/kg of prednisolone) for four weeks, after which she had normalization of renal function and was normotensive.

Figure 1. (HE stain): Acute tubulointerstitial nephritis with early tubular chronicity.

Figure 2. (PAS stain) Acute tubulointerstitial nephritis with early tubular chronicity.

Discussion

Renal lesions in patients with acute intermittent porphyria are attributed to hypertension but are not certain.³ Increased porphyrin metabolism during an attack is a plausible cause of renal impairment. During an acute episode, excess amounts of porphyrin metabolites that are produced can cause cytotoxic or vasospastic renal vascular lesions, inducing high blood pressure and later progressing to chronic hypertension.⁴ Other factors such as vasopressin and angiotensin may also be additives that cause kidney injury.

In a study by Andersson et al., 9 patients with acute intermittent porphyria who underwent renal biopsy had hypertension.⁵ Biopsies from these patients showed varying (slight to extensive) degrees of nephrosclerosis, with a mean of 50% globally sclerotic glomeruli, moderate tubular atrophy, and interstitial fibrosis with vessel wall thickening. Acute porphyria rarely presents as acute interstitial nephritis. The precise mechanism underlying the development of acute tubulointerstitial nephritis remains unclear; however, it is postulated that metabolic intermediates or porphyrin precursors may contribute to this. Therefore, interstitial fibrosis and tubular atrophy in renal biopsy imply an advanced phase of initial acute tubulointerstitial nephritis, which ultimately culminates in chronic interstitial nephritis and, thus, persistent renal dysfunction. Therefore, our case demonstrates that the metabolic intermediates/porphyrin precursors ignited the process of tubulointerstitial nephritis, which eventually led to early tubular chronicity, as seen in renal biopsy.

Conclusion

This case highlights the unique renal presentation of acute intermittent porphyria, thus emphasizing that clinicians should consider acute tubulointerstitial nephritis as a possibility in patients with acute porphyria presenting with unexplained renal dysfunction. Through this report, the literature includes acute intermittent porphyria as a possible cause of acute tubulointerstitial nephritis.

Consent to participate

The patient gave written informed consent.

Consent to publish

Written consent was obtained from the patient for publishing the case after de-identifying and anonymizing all patient identifiers.