Nephrocalcinosis, urolithiasis and renal insufficiency sarcoidosis

Renal sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology. The pathogenesis rests on an aberrant T cell response to unidentified antigens in individuals predisposed by genetic and environmental factors. Increased expression of polarized macrophages and disequilibrium between effector and regulator T cells contribute to the formation of noncaseating granulomas, that are frequently found in affected organs. The main kidney abnormalities in sarcoidosis are granulomatous interstitial nephritis (GIN) and hypercalcemia-related disorders. The clinical diagnosis is difficult. The outcome is variable, ranging from spontaneous remission to end-stage kidney disease (ESKD). Early diagnosis and prompt treatment with corticosteroids can improve the prognosis. Hypercalcemia may be responsible for acute kidney injury (AKI) caused by vasoconstriction of afferent arterioles. Complications of persistent hypercalcemia include nephrocalcinosis and renal stones. In patients with ESKD, dialysis and transplantation can offer results comparable to those observed in patients with other causes of kidney failure. Based on a review of the literature, we present an overview of the etiopathogenesis, the renal manifestations of sarcoidosis and their complications, management and prognosis.

Renal manifestations of sarcoidosis: from accurate diagnosis to specific treatment

Sarcoidosis is a multisystem granulomatous disease characterized by epithelioid noncaseating granulomas associated with clinical and radiologic findings. The cause of this disease is still uncertain. Sarcoidosis affects mostly lungs and lymph nodes and is not usually considered a urological disease, therefore, this etiology may be overlooked in several urological disorders, such as hypercalcemia, hypercalciuria and nephrolithiasis. It affects all races and genders. This review aims to describe the urological manifestations of sarcoidosis and to elucidate how the disease may affect the management of numerous urological conditions.

Vitamin-D status and mineral metabolism in two ethnic populations with sarcoidosis

Vitamin-D insufficiency and sarcoidosis are more common and severe in African Americans (AA) than Caucasians. In sarcoidosis, substrate-dependent extrarenal 1,25-dihydroxyvitamin-D (1,25-(OH)2D) production is thought to contribute to hypercalciuria and hypercalcemia, and vitamin-D repletion is often avoided. However, the anti-inflammatory properties of vitamin-D may also be beneficial. We prospectively examined serum vitamin-D levels, calcium balance, and the effects of vitamin-D repletion in 86 AA and Caucasian patients with biopsy-proven active sarcoidosis from the USA (US) and Italy (IT) in university-affiliated outpatient clinics. Clinical features, pulmonary function, and calciotropic hormones were measured. 16 patients with vitamin-D deficiency and normal serum ionized calcium (Ca(2+)) were treated with oral ergocalciferol (50,000 IU/week) for 12 weeks. Baseline mineral parameters were similar in US (93% AA) and IT (95% Caucasian) patients irrespective of glucocorticoid treatment. Pulmonary dysfunction was less pronounced in IT patients. Nephrolithiasis (in 11% US, 17% IT patients) was associated with higher urinary calcium excretion. Vitamin-D deficiency was not more prevalent in patients compared to the respective general populations. As serum 25-hydroxyvitamin-D (25-OHD) rose postrepletion, serum 1,25-(OH)2D, γ-globulins, and the previously elevated angiotensin converting enzyme (ACE) levels declined. Asymptomatic reversible increases in Ca(2+) or urinary calcium/creatinine (Ca/Cr) developed in three patients during repletion. In conclusion, Caucasian and AA patients show similar calcium and vitamin D profiles. The higher prevalence of hypercalciuria and nephrolithiasis in sarcoidosis is unrelated to endogenous vitamin-D levels. Vitamin-D repletion in sarcoidosis is generally safe, although calcium balance should be monitored. A hypothesis that 25-OHD repletion suppresses granulomatous immune activity is provided.

Urological manifestations of sarcoidosis

PURPOSE

We describe the urological manifestations of sarcoidosis and how the disease may affect the management of multiple urological conditions.

MATERIALS AND METHODS

We performed a PubMed® search using the query sarcoidosis and multiple urological terms.

RESULTS

Sarcoidosis is a disease that has variable manifestations. There is often genitourinary involvement that is clinically silent. However, sarcoidosis may cause symptoms, such as nephrolithiasis, which are sometimes the first manifestation of the disease. Renal function may be affected, and appropriate recognition and treatment may avert progressive functional decline. The presence of sarcoidosis may also confound the diagnosis and staging of various urological malignancies, particularly renal and testicular carcinoma.

CONCLUSIONS

Urologists should be aware of the urological manifestations of sarcoidosis to avoid misdiagnoses and the over staging of urological cancers, and to identify when it is an underlying cause of nephrolithiasis or obstructive uropathy.

Nephrolithiasis as a presenting feature of chronic sarcoidosis

BACKGROUND

Renal calculi have been reported to occur in about 10% of patients with chronic sarcoidosis, but nephrolithiasis as a presentation of this disease has not been studied.

METHODS

The charts of 618 patients with histologically proven sarcoidosis, seen in the period October 1978-1992, were reviewed in order to identify nephrolithiasis at presentation.

RESULTS

Seventeen patients had renal calculi which preceded other manifestations of sarcoidosis. In six the occurrence of calculi suggested the diagnosis. Another eight patients had a previous history of recurrent colic with calculi. The time intervals between the first calculus and the appearance of other manifestations of sarcoidosis ranged from one to 25 years, but it was over four years in only two cases and all had at least one calculus in the year before the diagnosis was made. In the other three patients appearance of the calculus was distant in time and was probably unrelated to their sarcoidosis. In most cases the sarcoidosis was chronic and needed long term treatment with corticosteroids. Four patients had further calculi during follow up (one month to 16 years) due to an improper withdrawal of treatment decided by the patient in two cases, and to the reduction in the corticosteroid dose in the other two.

CONCLUSIONS

Calculi were the presenting feature of sarcoidosis in six (1%) patients, and were the first manifestation of the disease in a total of 14 (2.2%). This frequency is over 20 times the likely incidence of calculi in the general population. Renal calculi may therefore be a rare primary manifestation of sarcoidosis. In such cases the disease is likely to be chronic and to require long term corticosteroid therapy. Sarcoidosis should always be suspected in cases of nephrolithiasis of unknown origin.

Acute renal failure due to sarcoid granulomatous infiltration of the renal parenchyma

A 56-year-old female with evidence of multisystem involvement due to sarcoidosis presented with acute renal failure. Percutaneous renal biopsy revealed sarcoid granulomatous infiltration of the renal parenchyma. Steroid therapy resulted in a prompt improvement of renal function. A review of the literature has disclosed 16 similar cases. Pertinent clinical and laboratory data and treatment regimens are discussed.