Calcium Kidney Stones

Pathogenesis, Evaluation, and Treatment Options

Helen L. Figge, RPh, PharmD, MBA

Disclosures

US Pharmacist 

In This Article

Patient Evaluation and Management

Patients who present for the first time with renal colic are often evaluated with an unenhanced helical CT scan. This is generally the most sensitive method for establishing the presence of a renal stone. The CT provides valuable information regarding the size and location of the stone(s), and any anatomical abnormalities can be defined. Ureteral stones smaller than 5 mm will generally pass spontaneously with adequate hydration. In the absence of fever, infection, or renal failure, these stones are generally followed conservatively. Pain may be managed with opioid analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs). Intravenous hydration is usually administered until the patient is able to consume adequate amounts of fluid by mouth. Most of these patients can be stabilized in the emergency room and then followed as an outpatient. Alpha1-adrenergic receptor blockers or calcium channel blockers are sometimes prescribed to assist with stone passage. Stones greater than 10 mm will generally not pass spontaneously and will require urologic intervention. Stones ranging from 5 mm to 10 mm will have variable outcomes. More distal stones will generally pass more readily than stones in the proximal ureter. Again, if the patient is afebrile, pain is controlled, and there is no evidence of infection or renal failure, the patient can be followed initially conservatively. Stones in this size range that do not pass will require intervention.[3]

Patient evaluation should include an assessment of potential contributing factors and risk factors, as previously discussed. Fluid intake, diet, calcium intake, sodium intake, oxalate intake, lifestyle, and medications should be reviewed. Family and personal history should be reviewed to uncover any clues regarding genetic components or systemic illness. Analysis of the stone composition is critical for ongoing management. Basic laboratory evaluation should include renal function, urinalysis, and electrolyte, calcium, and phosphorus levels. If the calcium is in the upper normal range or is elevated, intact parathyroid hormone should be obtained to rule out hyperparathyroidism.[3]

Once the acute episode has passed, certain patients should undergo a complete laboratory evaluation. This is appropriate in patients in demographic groups not typically susceptible to stone formation, in children, and in those with an increase in the number or size of stones. The laboratory evaluation should include a 24-hour urine collection for determination of calcium, oxalate, citrate, sodium, phosphorus, and creatinine levels.[3]

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