Renal Calculi (Kidney Stones)
by Online Nursing Classes

Renal Calculi
- Common name; Kidney Stones

- It is most common in men (they have physiologic hypertrophy of the prostate at age 50 and above, increasing residual urine volume of stasis and predisposing precipitation of organic crystals).

- Calcium stone is the most common constituent of this condition (hypercalcemia or hyperthyroidism predisposes this condition).

- 99% of calcium is in the bone and teeth and resorption occurs during immobility (which is why incidence is high among bedridden patients).

Risk Factors

• Infection
• Urinary stasis
• Obstruction
• Other metabolic conditions

Subjective Findings are:

• Flank pain (dull to excruciating)

• It is radiating depending on the stone movement

Objective Findings are:

• Crystals in urine (calcium, struvite, uric acid or cystine); increased serum calcium, phosphorus or uric acid

Types of Stones

1. Calcium phosphate

• Caused by supersaturation of urine with calcium and phosphate
• Diet includes acid ash foods because calcium stones have an alkaline chemistry
• Phosphate sources include vitamin D rich foods

2. Calcium oxalate

• Caused by supersaturation of urine with calcium and oxalate
• Oxalate food sources include tea, almonds, cashews, chocolate, cocoa, beans, spinach, and rhubarb

3. Struvite

• Also called triple phosphate, composed of magnesium and ammonium phosphate
• Forms in alkaline urine

4. Uric Acid

• Due to excess dietary purine or gout
• Forms in acidic urine

5. Cystine

• Due to increased amounts of methionine (an essential amino acid that forms cystine)


• Renal colic that starts in the lumbar region that radiates to the testicles in men and bladder in women
• Ureteral colic that radiates toward genitalia and thigh
• Sharp severe pain of sudden onset
• N/V, pallor, urinary frequency with alternating retention
• Low grade fever, signs of UTI
• Hematuria

Diagnostic and Laboratory Findings for Renal Calculi

• Urinalysis may reveal hematuria, pyuria, and crystal fragments
• 24-hour urine levels for calcium, uric acid, and oxalate
• Serum calcium, phosphorus, and uric acid levels
• KUB, IVP, retrograde pyelography, renal ultrasound, CT scan, cystoscopy, and MRI

Nursing Interventions

Strain urine (for passage of small stones that should be sent to laboratory for studies)
Force fluids up to 3-4 L/day, unless contraindicated
• Encourage activity
• Warm soaks to reduce spasms
• Administer analgesics as prescribed on regular schedule
• Diet modification


• Cheeses
• Cranberries
• Eggs
• Fish
• Grains (beans and cereals)
• Meats
• Plums
• Poultry
• Prunes
• Gelatin
• Ascorbic acid


• All fruits except cranberries, prunes, plums
• Most vegetables including rhubarb
• Milk

Read other nursing concepts related to renal calculi in this page.

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