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BACKGROUND Malaria adversely affects the kidney in a variety of ways. The most common kidney injury is acute tubular necrosis, although various glomerular lesions are also described. Of these, collapsing focal segmental glomerulosclerosis (cFSGS) is the most rarely seen. Thus, the natural history of this lesion and response to treatment are not clear. Herein, we present a case of cFSGS complicated by acute interstitial nephritis caused by Plasmodium falciparum (P. falciparum) unresponsive to prednisone. CASE REPORT A 64-year-old Nigerian man with chronic kidney disease due to hypertensive nephropathy was admitted to the hospital, diagnosed with active P. falciparum malaria infection after returning from Nigeria. He developed acute kidney injury and nephrotic range proteinuria. Renal biopsy showed acute interstitial nephritis and cFSGS. Despite corticosteroid therapy, his kidney function worsened, requiring initiation of renal replacement therapy. This is the fifth case report of cFSGS due to malaria P. falciparum but the first to report the presence of acute interstitial nephritis in association with cFSGS due to malaria. CONCLUSIONS cFSGS is rarely seen as a manifestation of P. falciparum infection. When associated with acute interstitial nephritis, the prognosis seems to be worse. It appears that age and co-morbidities are the risk factors for unresponsiveness to corticosteroids, and treatment of the renal disease should focus on rapidly eradicating the parasitemia and providing supportive care. Our case report is the first to describe a combination of cFSGS and interstitial nephritis caused by P. falciparum unresponsive to corticosteroids.

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Hypercalcemia is often seen in patients with malignancies, and in the past treatment for this has traditionally included loop diuretics. Clinically, patients with hypercalcemia frequently present with polyuria and volume contraction which may be further exacerbated by diuretic therapy. In the lab, hypercalcemia has been shown to activate the calcium-sensing receptor in the thick ascending limb of Henle and inactivate the 2 chloride sodium potassium co-transporter and induce a hypokalemic metabolic alkalosis, an effect similar to that of the loop diuretic furosemide. We now report what may well be the first clinical correlate of this laboratory finding in a patient who developed a hypokalemic metabolic alkalosis as a consequence of severe hypercalcemia due to multiple myeloma and whose metabolic derangement was corrected without the use of a loop diuretic which may have exacerbated the electrolyte abnormalities.

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BACKGROUND: In patients with congestive heart failure (CHF), continuous diuretic therapy may result in acute renal insufficiency (ARI). This study examines factors contributing to this complication. METHODS: We analyzed clinical data from 318 consecutive patients who were hospitalized for CHF. All were treated with diuretics and had echocardiography performed within 4 days of hospitalization. Systolic left ventricular (LV) dysfunction is defined as an ejection fraction less than 50%, and diastolic LV dysfunction, as an ejection fraction of 50% or greater in the presence of LV hypertrophy and a reversed E/A ratio. RESULTS: ARI, defined as a 25% increase in serum creatinine level, occurred in 110 patients (35%) after diuretic therapy. Risk factors for ARI on univariate analyses were older age, higher baseline serum creatinine level, lower baseline serum sodium level, lower mean arterial pressure (MAP) during diuretic therapy, and greater doses and longer duration of diuretic therapy. In multivariate analyses, ARI occurred more frequently in patients with systolic (40%) than diastolic dysfunction (28%). The use of digoxin in patients with systolic LV dysfunction was observed to decrease the risk for ARI by 61%, independent of other agents used for the treatment of patients with CHF. CONCLUSION: Age, baseline renal function and serum sodium concentration, MAP, and intensity of diuretic therapy can identify individuals at risk for ARI while receiving diuretic therapy for CHF. This complication is observed more often in individuals with systolic dysfunction, and its risk may be decreased with the use of digoxin.

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The patient, a 78-year-old Asian male, was brought to the hospital because of acute shortness of breath that had progressively worsened over the course of the day. He complained of a nonproductive cough and claudication after walking 1 block. His past medical history was significant for mild renal insufficiency (serum creatinine 1.5--2.0 mg/dl), the etiology of which was never explored. Although there was a recent history of mild to moderate hypertension, at presentation his blood pressure was noted to be 240/118 mm Hg in both arms. His physical exam at the time of admission was remarkable for grade II hypertensive retinopathy, an S4 gallop, periumbilical systolic bruits, audible femoral arterial bruits and absent distal lower extremity pulses. Initial complete blood count, serum electrolytes and cardiac enzymes (including lactate dehydrogenase) were normal. His blood urea nitrogen and serum creatinine concentrations were 51 and 3.6 mg/dl, respectively, and his urinalysis showed 1+ protein (both by dipstick and sulfasalicylic acid) with a "benign" sediment (0--1 WBC/HPE, 1--2 RBCs/HPF) with occasional granular casts. His electrocardiogram, apart from demonstrating left ventricular hypertrophy with secondary ST-T wave abnormalities, showed no acute changes; his chest X-ray demonstrated cardiomegaly and pulmonary vascular congestion. He was intubated and subsequently treated with increasing parenteral doses of furosemide (40--240 mg) and a nitroglycerine drip (up to 15 mcg/min). Over the course of the first 48 h, his blood pressure was gradually lowered to 170/100 mm Hg. His urine output increased from 20 ml/h to 125/ml/h, and his respiratory status improved, allowing him to be extubated. In spite of adequate control of his blood pressure in the ensuing days (150--170/80--90 mm Hg), his renal function continued to deteriorate. Renal sonography (without Doppler) demonstrated a right kidney of 9.6 cm and a left kidney of 9.3 cm in length without evidence of hydronephrosis. Both kidneys were noted to be echogenic. Assays for antinuclear antibodies and antineutrophilic cytoplasmic antibodies were negative, and the patient's serum complement levels were normal. For several days after his admission, his serum creatinine gradually rose to 10.7 mg/dl, and hemodialysis was initiated for uremic encephalopathy. Because of the high index of suspicion for renal artery stenosis as the case of both his hypertension and renal failure, a renal angiogram was performed. It revealed a 90% occlusion of the right renal artery with ostial involvement and a 70% occlusion of the left renal artery; both kidneys had poor distal renal vasculature and there was marked atherosclerotic disease of the aorta. After being hemodialyzed for 3 treatments, his renal function began to improve spontaneously. His serum creatinine returned to 3.4 mg/dl, and a subsequent 24-hour urine demonstrated a creatinine clearance of 20 ml/min and an excretion of 1.2 g of protein. Following his discharge from the hospital, his renal function remained unchanged for 3 years, and his blood pressure was easily controlled on monotherapy with a long-acting calcium channel blocker. He recently died from pneumonia.