Hematuria and Hypercalciuria
also see Vin-rose urine

Hematuria

• Abnormal if more than 5 RBCs per high-power microscopic field from a centrifuged midstream voided urine sample (positive dipstick with >2 RBCs per hpf).
• Hemoglobin and myoglobin can also cause a positive dipstick for heme (with a negative microscopic exam)
• Discolored urine can result from certain foods and drugs (e.g., sulfonamides, flagyl, nitrofurantoin)
• Distinguish upper vs. lower tract:
  • Non-glomerular origin often associated with bright red color, normal RBCs in size and shape, normal urinary protein excretion, and absence of RBC casts
  • Upper tract (glomerulus or renal parenchyma) often characterized by brown/smokey/tea color, casts, dysmorphic RBCs, >1+ proteinuria

Differential of Hematuria without proteinuria

• UTI

• Hypercalciuria

• Thin basement membrane disease

• Sickle cell disease or trait

• Renal cystic disease

• Nephrolithiasis

• Renal anatomic abnormalities

Differential of hematuria with proteinuria

• UTI

• PSAGN

• IgANephropathy

• HSP

• MPGN

• Lupus nephritis

• Alportsyndrome

• HUS

• Other forms ofglomerulonephritis

Familial causes of hematuria:polycystic kidney disease, thin basement membrane disease, sickle cell disease or trait, Alport syndrome, hypercalciuria with family history of nephrolithiasis

Workup of persistent hematuria

Lower tract:

• Consider a urine culture, sickle cell prep in African-Americans, urinary Ca/Cr ratio, serum creatinine, C3, streptozymetiter

• Consider kidney/bladder ultrasound to r/o polycystic kidney dz, tumor, UPJ obstruction, and stones

Upper tract:

• Consider a CBC, C3, C4, ASO titer, streptozyme titer, electrolytes, BUN, Cr, albumin, SC prep, quantitative protein excretion

• Consider tests for SLE, Hep B, antinuclear cytoplasmic antibody titer

• Renal ultrasound

• Screening urinalysis on first-degree family members

• Renal biopsy if etiology remains unclear

Discussion of some conditions in the differential dx

- Hypercalciuria

- Benign familial hematuria (BFH) should be considered in any child who has hematuria. Therefore, family members should have their urine tested for blood. In general, BFH is considered a diagnosis of exclusion.

- Any form of renal cystic disease may cause RBCs to appear in the urine. However, multicystic kidney dysplasia (MKD) is a rare cause of hematuria in infants. This congenital malformation almost always is unilateral and most frequently is detected on routine ultrasonographic screening during pregnancy. Ultrasonography will reveal multiple cysts scattered throughout the renal parenchyma, with marked echogenicity of the parenchyma, indicating nonspecific renal dysplasia. A renal scan will distinguish between hydronephrosis and MKD. There is no treatment for MKD.
 
- The most common renal tumor of childhood is Wilms tumor. In general, affected children will have a large abdominal mass that often is detected initially by a parent. There may be abdominal pain if the mass extends throughout the abdomen. However, Wilms tumor is an unusual cause of RBCs in the urine in children.

- The complete urinalysis required to evaluate urine for the presence of RBCs offers other potentially diagnostic indices, including the presence of protein, white blood cells (WBCs), and nitrites. Protein in the urine may indicate renal  disease, and in conjunction with RBCs suggests renal parenchymal injury. The presence of many WBCs, RBCs, and  nitrites in the urine is highly suggestive of a urinary tract infection.

References:
Alon US, Berenbom A. Idiopathic hypercalciuria of childhood: 4- to
11-year outcome. Pediatr Nephrol. 2000;14:1011-1015
Coe FL, Parks JH, Moore ES. Familial idiopathic hypercalciuria. N Engl J
Med. 1979;300:337-340
Stapleton FB, Noe HN, Roy C III, Jerkins G. Hypercalciuria in children
with urolithiasis. Am J Dis Child. 1982;136:675-678