Diagnosis

All patients should have a basic work up to rule out systemic causes of nephrolithiasis. 

Comprehensive evaluation needs to be done for the following patients:

• All children
• Patients in the demographic group in which stones are not expected
• Patients with growing or recurrent stone (metabolically active disease)
• Patients with a strong family history of stones
• Patients with systemic diseases or underlying metabolic disorders that predispose to stone formation
• When the recovered stone is not composed predominantly of calcium oxalate
• Solitary kidney

A detailed evaluation should be undertaken 3 to 4 weeks after the last episode of renal colic, and as the patients resume their normal fluid and dietary intakes.

Medical History

• Chronology of stone events
• Presence of systemic diseases or underlying metabolic disorders that enhance stone formation
• The presence of a family history of stones
• Intake of medication that can increase the risk of stone formation
• Occupation and life style
• The analysis of previous stones

Physical Examination
May provide clues to underlying systemic causes

Laboratory Tests

• Urinalysis
• Urine culture
• Cystine screening
• Blood tests
• Twenty-four hour urine collection; total urine volume, pH, calcium, citrate, magnesium, oxalate, phosphate, sodium uric acid (cystine, if screening test is positive), and creatinine
• Stone analysis. With x-ray crystallgraphy or infrared spectrography.
• Urinary acidification test

Radiologic Evaluation

• Plain film of the kidneys, ureter, and the bladder (KUB)
• Intravenous pyelogram (IVP)
• Ultrasonographv (US)
• CT scans

Clinical Manifestations of Nephrolithiasis

• Asymptomatic nephrolithiasis may be discovered during the course of radiographic studies undertaken for unrelated reasons
• Pain is the most common symptom; mild ache to severe intense pain requiring hospitalization and parenteral analgesic medications
• Hematuria may be absent if the stone is causing complete obstruction
• Nausea and vomiting are frequently associated with renal colic
• Frequency, urgency, and dysuria can result from stone impaction at the ureterovesical junction and/or associated urinary tract infection
• Low-grade fever without associated infection
• Staghorn calculi do not produce symptoms unless small pieces break off and pass into the ureter. They can cause chronic renal failure over years if present bilaterally

Indications for a Metabolic Stone Evaluation
Recurrent stone formers
Strong family history of stones
Intestinal disease (particularly chronic diarrhea)
Pathologic skeletal fractures
Osteoporosis
History of urinary tract infection with calculi
Personal history of gout
Infirm health (unable to tolerate repeat stone episodes)
Solitary kidney
Anatomic abnormalities
Renal insufficiency
Stones composed of cystine, uric acid, struvite

Evaluation of Single Stone Formers
History
Underlying predisposing conditions (per Table 46–1)
Medications (calcium, vitamin C, vitamin D, acetazolamide, steroids)
Dietary excesses, inadequate fluid intake or excessive fluid loss

Multichannel blood screen

Basic metabolic panel (sodium, potassium, chloride, carbon dioxide, blood urea nitrogen, creatinine)
Calcium
Intact parathyroid hormone
Uric acid

Urine
Urinalysis
pH > 7.5: infection lithiasis
pH < 5.5: uric acid lithiasis
Sediment for crystalluria

Urine culture

Urea-splitting organisms: suggestive of infection lithiasis

Qualitative cystine

Radiography
Radiopaque stones: calcium oxalate, calcium phosphate, magnesium ammonium phosphate (struvite), cystine
Radiolucent stones: uric acid, xanthine, triamterene

Intravenous pyelography: radiolucent stones, anatomic abnormalities
Stone analysis

Abbreviated Protocol for Low-Risk Single Stone Formers
• A complete medical history should be obtained from all stone formers.
• Patients should be screened for medical diseases that predispose to calculi.
• Serum metabolic panel and urinalysis are obtained.
• Urine microscopy for crystals may provide clues to diagnosis.
• Stone analysis may improve the accuracy of further evaluation.
• Basic radiography (plain films) screen for remaining calculi.

Simplified Metabolic Evaluation
• A simplified metabolic evaluation has been established.
• Commercial laboratories may facilitate the collection of 24-hour urine studies.
• There is no consensus regarding the need for one versus two 24-hour urine collections during an initial evaluation (although the authors prefer two collections).

Use of Stone Analysis to Determine Metabolic Abnormalities
• Stone analysis may obviate the need for a complete metabolic evaluation.
• Stone composition can direct metabolic investigation.

Radiologic imaging is used for determination of the presence or absence of calculi, renal anatomy, and associated findings (i.e., hydronephrosis). As such, diagnostic imaging plays a crucial role in the surgical planning and follow-up of patients with nephrolithiasis. Aside from the inability to identify pure uric acid stones on plain radiography compared with CT, diagnostic imaging has not historically proven to be beneficial in the medical evaluation and management of stone disease.

In the United States, bladder calculi usually occur in men older than 50 years and are usually associated with bladder outlet obstruction. The diagnosis of a bladder stone should result in a complete urologic evaluation for factors that cause urinary stasis such as urethral stricture, benign prostatic hyperplasia, bladder diverticulum, and/or a neurogenic bladder. Occasionally, bladder stones may result as a consequence of a retained foreign body.
Medical management of Bladder Calculi

In contrast to renal stones, bladder stones are usually composed of uric acid (in noninfected urine) or struvite (in infected urine). Reports from the United States revealed uric acid stones in nearly 50% of patients with bladder stones (Douenias et al, 1991). Such patients often have bladder outlet obstruction, causing them to decrease fluid intake with the resultant production of concentrated, acidic urine. The occurrence of calcium oxalate or cystine stones in the bladder suggests the presence of calculi in the kidney with subsequent ureteral passage and entrapment in the bladder.

The typical symptoms of a vesical stone are intermittent, painful voiding and terminal hematuria. Discomfort may be dull, aching, or sharp suprapubic pain, which is aggravated by exercise and sudden movement. Severe pain usually occurs near the end of micturition, as the stone becomes impacted at the bladder neck.
Besides pain, there may be an interruption of the urinary stream from impaction of the stone at the bladder neck or urethra.