Patchy renal vasoconstriction in rhabdomyolysis-related acute renal failure

Acute Renal Failure with Severe Loin Pain and Patchy Renal Vasoconstriction in a Patient without Hypouricemia, Provoked by Epileptic Seizure

A 26-year-old Japanese man without hypouricemia and with 3 previous episodes of seizures concurrent with acute kidney injury (AKI) was admitted due to an epileptic seizure, lower back pain and AKI. His creatinine kinase levels were slightly elevated. Patchy renal ischemia on contrast-enhanced computed tomography and persistent residual contrast medium was observed, consistent with acute renal failure with severe loin pain and patchy renal ischemia after anaerobic exercise (ALPE). Diffusion-weighted imaging (DWI) demonstrated signal changes in the corresponding area. ALPE should be considered a cause of AKI following seizures. We recommend DWI as an alternative diagnostic modality.

Clinical characteristics of acute renal failure with severe loin pain and patchy renal vasoconstriction

BACKGROUND

Acute renal failure (ARF) with severe loin pain and patchy renal vasoconstriction (PRV) is a syndrome presenting with sudden loin pain after anaerobic exercise. We aimed to investigate the clinical characteristics and the efficacy of diagnostic imaging studies of patients with this syndrome.

METHODS

We retrospectively selected 17 patients with ARF accompanied by loin or abdominal pain who showed multiple patchy wedge-shaped delayed contrast enhancements on a computerized tomography scan. Information about the clinical characteristics, including the nature of pain and combined symptoms, suspected causes, such as exercise, drug or alcohol intake, and renal hypouricemia, and the results of laboratory and imaging tests were gathered.

RESULTS

The mean age of patients with episodes of ARF accompanied by loin pain was 23.0±6.5 (range 16-35) years old. Pain was mainly located in the loin (70.6%) or abdominal area (76.5%) and continued for approximately 3.5±4.0 days. Exercise was suspected as a primary cause of disease in 12 (70.6%) patients. Maximal serum creatinine was 5.42±3.16 (1.4-12.1) mg/dL 3.1±1.8 (1-7) days after the onset of pain. The peak level of serum uric acid was 9.41±2.91 (6.0-15.8) mg/dL. All of the patients recovered to near-normal renal function, and one patient showed hypouricemia after recovery.

CONCLUSION

ARF with severe loin pain and PRV can present with loin or abdominal pain, even without a history of anaerobic exercise. Careful history taking and appropriate imaging studies are critical in the diagnosis and management of this syndrome.

Contribution of myoglobin-induced increases in vascular resistance to shock decompensation in experimental Crush-syndrome in anesthetized rats

Myoglobin is known to become nephrotoxic when released in greater amounts from skeletal muscle into the general circulation during shock. The present study deals with the question as to whether a myoglobin-induced increase in vascular tone additionally contributes to the detrimental role of this protein in hypovolemic shock. Anesthetized rats were subjected to 250 mg kg x h(-1) myoglobin infused i.v. during hemorrhagic hypotension of 50 mmHg. Shock survival time was measured, as were blood flow and vascular resistance in kidney, intestine, brain, and heart, using the microsphere method. Rats subjected to only myoglobin or hemorrhage survived a period of >120 min; in contrast, rats, exposed to both myoglobin and hemorrhage died at 68 +/- 9 min. When the animals subjected to only hemorrhage and to myoglobin/ hemorrhage were compared, significantly lower values were found in the latter group with respect to blood flow in the kidney (1.7 +/- 0.1 vs. 0.2 +/- 0.05 ml x min(-1) x g(-1)), small intestine (1.0 +/- 0.1 vs. 0.5 +/- 0.1 ml x min(-1) x g(-1)), cardiac output (112 +/- 5 vs. 62 +/- 10 ml(-1) x min(-1) x kg(-1)), and significantly higher values of total peripheral vascular resistance (0.45 +/- 0.02 vs. 0.81 +/- 0.12 mmHg x min x ml(-1) x kg) at 50 min of hypotension. It is assumed that these effects of myoglobin are induced by its ability to scavenge endogenous nitric oxide, because a modified, non-nitrosylable myoglobin was unable to induce such effects. The results support the view that a pathological release of myoglobin into the general circulation causes increases in vascular resistance of vital organs that may contribute to decompensation of tissue supply when occurring in hypovolemic shock.

Atypical low-signal-intensity renal parenchyma: causes and patterns

Certain renal diseases manifest as low signal intensity of the renal parenchyma on magnetic resonance images. Sometimes, the appearance is sufficiently characteristic to allow a specific radiologic diagnosis to be made. The causes of this finding can be classified into three main categories on the basis of the pathophysiology: hemolysis, infection, and vascular disease. The first category includes paroxysmal nocturnal hemoglobinuria (PNH), hemosiderin deposition in the renal cortex from mechanical hemolysis, and sickle cell disease. The second category includes hemorrhagic fever with renal syndrome (HFRS). The third category includes acute renal vein thrombosis, renal cortical necrosis, renal arterial infarction, rejection of a transplanted kidney, and acute nonmyoglobinuric renal failure with severe loin pain and patchy renal vasoconstriction. These disease processes have different patterns of low signal intensity. PNH, hemosiderin deposition from mechanical hemolysis, and sickle cell disease involve the entire cortex including the columns of Bertin. HFRS involves the medulla, especially the outer medulla, whereas cortical necrosis involves the inner cortex including the columns of Bertin. In renal vein thrombosis, low-signal-intensity lesions involve the outer medulla, an appearance resembling that of HFRS. Wedge-shaped low-signal-intensity regions involving both the cortex and the medulla are seen in arterial infarction.