[Renal manifestations of sarcoidosis. A report of nine cases]

Kidney manifestations of sarcoidosis

Renal involvement is a clinically relevant organ manifestation of sarcoidosis, leading to increased morbidity and complications. Although the exact incidence remains unknown, renal disease is likely to occur in up to one third of all sarcoidosis patients. Every patient with newly diagnosed sarcoidosis should receive a renal work-up and screening for disrupted calcium metabolism. Amid various forms of glomerulonephritis, granulomatous interstitial nephritis is the most common one, but it rarely leads to renal impairment. Histologically, granulomas can be absent. Nephrocalcinosis and nephrolithiasis are frequent forms when hypercalcaemia or hypercalciuria occur. Drugs used for treatment of systemic sarcoidosis can also cause renal damage. Due to its high heterogeneity, renal sarcoidosis can be difficult to treat. Glucocorticoids and various immunosuppressive treatments have been proven to be effective based on case series, but clinical trials are lacking. A treatment guideline for renal sarcoidosis is urgently needed. In this review article, we present an overview of the different forms of renal sarcoidosis and the diagnostic steps to confirm renal involvement; in addition, we provide insights on the management and available treatments. A better understanding regarding the pathogenesis of sarcoidosis is the key for the development of more specific, targeted therapies.

Renal sarcoidosis: approach to diagnosis and management

PURPOSE OF REVIEW

The purpose of this article is to provide understanding of renal sarcoidosis, the different types of renal sarcoidosis, disease burden of renal involvement, and treatment options.

RECENT FINDINGS

The frequency of renal involvement seems to be underestimated, but renal sarcoidosis represents a relevant group of organ manifestations and significantly adds to the patient's morbidity. Because histopathological analysis of renal biopsy specimens can reveal various entities, a diagnostic workup is necessary in every patient with sarcoidosis.

SUMMARY

If systematically screened for renal manifestations are likely to occur in up to 25-30% of all sarcoidosis patients. The most common histological form of renal sarcoidosis is the granulomatous interstitial nephritis; however, granulomas can be absent. Furthermore, one can find various forms of secondary glomerulonephritis. In cases with dysregulated calcium homeostasis, nephrocalcinosis and nephrolithiasis are commonly detectable kidney diseases. AA amyloidosis or renal masses because of granuloma formation are considered to be rare manifestations. In addition to glucocorticoids various immunosuppressive treatments such as tumor necrosis factor alpha inhibitors have proven to be effective based on case series.

[Systemic sarcoidosis and membranous glomerulonephritis]

Renal involvement in sarcoidosis is rare and more often related to calcium metabolism disorders or granulomatous interstitial nephritis. Glomerulonephritis is exceptional. There may be a long latency period between the development of active sarcoidosis and glomerular involvement and inversely. We report a case membranous glomerulonephritis revealing systemic sarcoidosis.

Renal sarcoidosis with normal serum vitamin D and refractory hypercalcemia

INTRODUCTION

Sarcoidosis is a multi-system disorder characterized by non-caseating epithelioid granulomas in multiple organs. Renal involvement may usually occur as granulomatous interstitial nephritis, but renal failure is uncommon. We report a case of renal-limited sarcoidosis diagnosed by renal biopsy, associated with abnormal calcium metabolism.

CASE PRESENTATION

A 30-year-old Caucasian male presented with unexplained renal function impairment and hypercalcemia. The patient did not have any history of kidney disease, cough, skin rash, dysuria, hematuria or any other symptoms. Physical examination was unremarkable. Serum creatinine was 2.2 mg/dl and serum calcium was 11.5 mg/dl. Serum intact parathyroid hormone level (12 pg/mL) was decreased. Serum angiotensin-converting enzyme (ACE), 1,25-dihydroxyvitamin D (1,alpha-25 vit D) and pre-proparathyroid hormone (PTHrP) levels and urinary calcium excretion were all in normal range. The renal biopsy showed severe interstitial nephritis with non-caseating granuloma. The patient was treated with prednisone with starting dose of 1 mg/kg. After 2 months of prednisone therapy, serum creatinine decreased. However, because of continued of hypercalcemia unresponsive to low calcium diet and prednisone, chloroquine was prescribed. Six months after the onset, the patient's serum creatinine is stable at 1.30 mg/dl, serum calcium is 10.8 mg/dl, and serum ACE and 1,alpha-25 vit D levels are in normal range. He does not have any signs of extra-renal relapse.

CONCLUSION

The mechanisms of abnormal calcium metabolism in this patient with renal-limited sarcoidosis are unclear.

[Renal failure in sarcoidosis]

Renal sarcoidosis is rare and may lead to renal failure in less than 3% of patients. It may occur as a consequence of calcium metabolism disorders or granulomatous interstitial nephritis. In this retrospective study, we present five patients with renal failure secondary to sarcoidosis diagnosed in our centre on one period of nine years. Patients were three males and two females with a mean age at the time of the diagnosis of 31,6 years. Pulmonary involvement was present in three cases. Renal biopsy revealed granulomatous interstitial nephritis lesions in all patients. Extra-membranous glomerulonephritis was present in one case. In another case, moderate interstitial fibrosis was observed. Corticosteroid therapy using prednisolone 1mg/kg per day was used in all patients. Three patients had methylprednisolone pulse before oral corticosteroid therapy. One patient required several sessions of haemodialysis. All patients were followed up for a mean period of 52,6 months (ranged from 13 to 84 months). All patients improved their renal function with normalization of creatininemia in two of them. Renal involvement in sarcoidosis is probably underestimated. Corticosteroids therapy is efficient and must be introduced early to prevent progression to chronic renal failure.

Renal sarcoidosis: clinical, laboratory, and histologic presentation and outcome in 47 patients

We conducted the current study to investigate the clinical, laboratory, and histologic features at presentation and the outcome of renal sarcoidosis (RS). Exhaustive retrospective data were collected by the French Sarcoidosis Group. Forty-seven adult patients were assessed (30 male/17 female, M/F ratio: 1.76). Median estimated glomerular filtration rate (eGFR) was 20.5 mL/min per 1.73 m(2) (range, 4-93 mL/min per 1.73 m(2)). Moderate proteinuria was found in 31 (66%) patients (median, 0.7 g/24 h; range, 0-2.7 g/24 h), microscopic hematuria in 11 (21.7%) patients, aseptic leukocyturia in 13 (28.7%) patients. Fifteen of 47 (32%) patients had hypercalcemia (>2.75 mmol/L). Eleven of the 22 (50%) patients diagnosed between June and September had hypercalcemia compared with only 4 of the 25 (16%) cases diagnosed during the other months (p < 0.001). Thirty-seven patients presented with noncaseating granulomatous interstitial nephritis (GIN), and 10 with interstitial nephritis without granulomas. Apart from hypercalcemia, the clinical phenotype was also remarkable for the high frequency of fever at presentation. All patients initially received prednisone (median duration, 18 mo), 10 received intravenous pulse methylprednisolone. eGFR increased from 20 +/- 19 to 44 +/- 24.7 mL/min per 1.73 m(2) at 1 month (p < 0.001, n = 38), to 47 +/- 19.9 mL/min per 1.73 m(2) at 1 year (p < 0.001, n = 46), to 49.13 +/- 25 mL/min per 1.73 m(2) at last follow-up (p < 0.001, n = 47). A complete response to therapy at 1 year and at last follow-up was strongly correlated with complete response at 1 month (p < 0.01). Renal function improvement was inversely related to initial histologic fibrosis score. A complete response to therapy at 1 year was strongly correlated with hypercalcemia at presentation (p = 0.003). Relapses were purely renal (n = 3) and purely extrarenal (n = 10) or both (n = 4), often a long time after presentation, with in some cases severe cardiac or central nervous system involvement. We conclude that hypercalcemia and fever at presentation are often associated with RS; RS is most often and permanently responsive to corticosteroid treatment, but some degree of persistent renal failure is highly frequent and its degree of severity in the long run is well predicted from both histologic fibrotic renal score and response obtained at 1 month.

Sarcoïdose et insuffisance rénale: à propos de deux cas

Renal involvement in sarcoidosis is rare and more often related to calcium metabolism disorders or granulomatous interstitial nephritis, glomerulonephritis is exceptional. The two cases of renal failure reported in this article illustrate the gravity of this complication, whose treatment remains difficult.