CLINICAL PRESENTATION OF RENAL DISEASE
The symptoms and signs of childhood renal disorders vary widely. Diagnostic clues are provided from the history, which should include a description of the amount, frequency, and color of the urine. Changes in any of these may herald a renal disease. The presence of symptoms such as pain on urination (dysuria), urgency (difficulty holding urine in the bladder), incontinence, or dribbling of the urinary stream in boys are also helpful. Pain is not typical of most renal diseases. However, flank pain is common with renal stones and pyelonephritis. Pain from renal stones is excruciating and often radiates from the flank toward the groin. Loin pain may occur with acute glomerulonephritis. Recurrent episodes of dehydration occur in disorders that affect water reabsorption or sodium retention such as tubular disorders, obstructive uropathy, and renal dysplasia. A history of maternal oligohydramnios suggests that in utero renal function was impaired. The family history is sometimes informative, especially in children with heritable kidney disorders such as Alport syndrome, hypercalciuria, cystinosis, and polycystic kidney.
Renal disorders also may present with more insidious symptoms or signs. Chronic renal failure commonly presents with nonspecific symptoms such as fatigue, sleep disturbances, headaches, nausea, and anorexia. Children with severe hypertension (frequently related to renal disorders) can present with seizures and changes in mental status (see Chapter 476). Anemia may occur due to a lack of erythropoietin production by the kidney.
Physical findings of hypertension and edema are common with renal disorders. Periorbital or dependent edema is often an early symptom. The presence of an abdominal mass or genital abnormalities may suggest a renal disease. The kidneys are easily palpated in the first week of life, and renal abnormalities such as multicystic dysplasia, hydronephrosis, and agenesis can be detected by abdominal palpation.
Urinalysis is one of the most useful procedures in evaluating patients who have suspected renal disease. However, some abnormalities on urinalysis are transient; therefore, repeated urinalyses is often useful to avoid more extensive and expensive evaluation.
The most informative urine to examine is the first morning specimen, as this often is the most concentrated and acidified, and possible increases in urine protein associated with an upright posture will be minimized. Unfortunately, the practical aspects of collecting first-morning urine often delays the time between urine collection and examination. When obtaining a urine culture, the external genitalia should be cleansed, especially in girls, to minimize contamination by extraneous material, such as vaginal cells. The choice of cleansing agent is important. Betadine may interfere with the dipstick reagents, so the usual recommended agent is benzalkonium. Female patients should be instructed to wipe front to back, to spread the labia while voiding, and to collect the urine after some has been passed to minimize bacterial contamination. Sitting backward on a standard toilet is helpful ...