Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (564 page)

   Laboratory Findings

   Progressive renal insufficiency with mild proteinuria (often <2 g/day). Urine sediment is typically normal.

   SRC is associated with acute kidney injury that is characterized by oliguria and sudden onset of proteinuria or hematuria. Microangiopathic hemolytic anemia and thrombocytopenia are also seen in some patients.

   Plasma renin activity is markedly elevated in SRC patients.

   Anti-RNA polymerase III autoantibodies are detected in one third of patients with SRC.

Suggested Reading

Bussone G, Bérezné A, Pestre V, et al. The scleroderma kidney: progress in risk factors, therapy, and prevention.
Curr Rheumatol Rep.
2011;13(1):37–43.

SICKLE CELL NEPHROPATHY

   Overview

   See sickle cell disease.

   Renal function abnormalities are common in sickle cell disease patients, and they include glomerular and tubular disorders. These abnormalities are mainly caused by sickling of RBCs in the microvasculature and usually associated with increased mortality.

   Generally, renal manifestations are more severe in patients with sickle cell disease (SCD) than those with sickle cell trait or combined hemoglobinopathies.

   Laboratory Findings

   Urinalysis: proteinuria is present in 15–40% of SCD patients and can be in the nephrotic range. Asymptomatic hematuria (microscopic, macroscopic, or gross) is common in SCD. Early decrease in the kidney concentrating ability is evident in patients with SCD leading to polyuria. This finding is less pronounced in patients with sickle cell trait.

   Low serum creatinine level due to hypersecretion in the proximal tubule and glomerular hyperfiltration is a common finding in young patients with SCD. Later in life, progressive decrease in GFR due to glomerular injury occurs with increased serum levels of BUN and creatinine.