Pediatric Urolithiasis Clinical Presentation

Stones are classified by their composition. Knowledge of composition may help to design preventive therapy, but the chemical composition of a stone usually has little to do with the clinical manifestations. The clinical manifestations are related more to the following 5 factors:

• The size of the stone (larger stones tend to be more symptomatic, although some large stones produce few symptoms)

• The location of the stone

• The production of urinary outflow obstruction

• The movement of the stone (eg, from the renal pelvis to bladder)

• The presence of infection

Presentation usually depends on age; symptoms such as flank pain and hematuria are more common in older children. Nonspecific symptoms (eg, irritability, vomiting) are common in very young children.

The following are 5 fairly typical presentations of stone disease in children:

• Intense pain that suddenly occurs in the back and radiates downward and centrally toward the lower abdomen or groin

• Hematuria, usually gross, occurring with or without pain: Hematuria may or may not be present. In a series of adults in whom helical computed tomography (CT) scanning was used to identify lithiasis in the emergency department (ED), one third had 5 or fewer red blood cells (RBCs) per high-powered field. ^[15] No similar study has been performed in children, but many pediatric nephrologists have identified stone disease children with symptoms, stones, and no hematuria.

• Infection leading to radiologic imaging in which a stone is identified

• Asymptomatic stones, which are sometimes identified when abdominal imaging is performed for another reason

• Persistent microscopic hematuria, which consists of 5 or more RBCs per high-power field in 3 of 3 consecutive centrifuged urine specimens obtained at least 1 week apart

History should include questions to identify frequent urinary tract infections, frequent bouts of abdominal pain, hematuria (gross or microscopic), passage of previous calculus, dietary intake (eg, oxalate, purine, calcium, phosphate, fructose, animal protein), drug intake (eg, anticancer drugs, glucocorticoids, allopurinol, loop diuretics), vitamin intake (A, D), fluid intake, habitual fluid type (eg, water, milk, tea, sports drinks),

The history should also include questions on chronic disease (eg, renal tubular acidosis, inflammatory bowel disease, short-gut syndrome, intractable seizures, cystic fibrosis), prior urologic surgery (eg, kidney transplant), or recent immobilization.

Because some renal stone diseases may be inherited, a careful family history to identify other family members with stones is important. In some reports, as many as 70% of children with idiopathic hypercalciuria (see Hypercalciuria) have a family history of stones. The cause of idiopathic hypercalciuria is unknown, but it may be transmitted as an autosomal dominant trait.

Other inherited conditions to be considered include cystinuria, an autosomal recessive defect of amino acid transport that leads to cystine kidney stones, glycinuria, a rare inherited renal tubular defect producing oxalate stones; xanthinuria, an autosomal recessive disorder that produces xanthine urolithiasis; and primary hyperoxaluria, produced by an autosomal disorder leading to oxalate stones. Several inherited disorders in purine metabolism lead to uric acid stones (Lesch-Nyhan disease is probably the best known).

The physical examination in children with urolithiasis is influenced by several factors. The most important include age, pain, infection, and the underlying process producing the stone.

For example, an infant with pain may have inconsolable crying; a teenager may have obvious costovertebral angle tenderness. Manifestations of infection may range from no physical abnormalities to fever to a physical picture consistent with urosepsis (eg, fever, tachycardia, hypotension, cold clammy skin). Conditions such as Lesch-Nyhan disease, inflammatory bowel disease (IBD), and cystic fibrosis have findings specific for the disease.

A routine physical examination should be performed, including the following anthropometric data:

• Height

• Weight

• Muscle mass

Systemic diseases associated with stones, including the following, may produce decreased growth:

• Distal renal tubular acidosis

• Oxalosis

• IBD

• Cystic fibrosis

• Short-gut syndrome

Many children with kidney stones have normal physical examination findings. Exceptions to normal findings on physical examination include the following:

• Hypertension (may be present with urinary obstruction or pain)

• Tachycardia in children with pain

• Costovertebral angle tenderness

• Oxalosis (flecked retina)

• Adolescents with primary hyperparathyroidism in whom stones are the presenting feature (eg, hypertension associated with hypercalcemia)

• Rickets, stones as part of Dent disease