Renal Calculi: Etiology and Risk Factors

• Renal calculi, also known as kidney stones, nephrolithiasis, or urolithiasis, result from mineral and salt buildup.
• These stones can lodge in the kidney or urinary tract, causing pain and hematuria.
• Approximately 80-90% of renal calculi pass spontaneously.

Etiology

• Formation is linked to dietary factors like high calcium, oxalate, or sodium, as well as urinary stasis and inadequate hydration.
• A common cause is low urinary volume due to insufficient hydration.
• Hyperparathyroidism contributes to calcium calculi.
• Uric acid stones are associated with high purine intake.
• Struvite stones and cystine stones (due to a metabolic defect) are other types.

Risk Factors

• Dietary, genetic, environmental, and lifestyle factors influence renal calculi formation.
• Age 43 and older is a risk factor, with highest rates between 40 and 65 years.
• Older individuals may have lower fluid and nutrient intake.
• Males are twice as likely to develop calculi.
• Obesity is linked to calculi formation.
• Environmental factors causing fluid/electrolyte imbalances, like extreme heat, increase risk.
• High protein/low carb diets, or diets high in calcium or salt, also elevate risk.

Comorbidities

• Coexisting conditions like hypertension, chronic kidney disease (CKD), and type 2 diabetes mellitus increase risk.

Epidemiology

• High incidence areas include the southern United States, Europe, Asia, Greenland, and parts of Australia.
• High temperatures are correlated with higher risk.

Signs and Symptoms

• Acute onset of flank pain is common.
• The pain is often sudden, sharp, severe, and constant, radiating to the groin, testicles, or labia.
• Nausea and vomiting frequently occur.
• Hematuria may be present.
• Fever/chills suggest systemic infection, possibly pyelonephritis.
• Pyelonephritis requires urgent surgery to relieve obstruction and decompress the kidney.

Testing

• KUB (kidney, ureter, bladder) X-ray can identify renal calculi but may miss small stones.
• Ultrasound detects obstruction and hydronephrosis.
• Non-contrast abdominal and pelvic CT scan is the most reliable.
• IV contrast is not recommended due to nephrotoxicity.
• Urinalysis assesses for leukocytes, bacteria, nitrites (infection indicators), blood, and crystals.

Environmental Factors

• Warmer climates increase the risk of renal stones.

Individual Factors

• Prevention relies on patient compliance with long-term medication use and dietary changes.

Education

• During acute episodes, instruct clients to strain their urine.
• Educate post-acute episode to prevent future stones.
• Advise diet modification: reduce calcium and restrict salt and protein intake.
• Increase water intake and activity level.
• Promote the DASH (Dietary Approaches to Stop Hypertension) diet.

Assessment

• Obtain health history including similar manifestations, diet, hydration, exercise habits, and existing conditions like hypertension, diabetes, and gout.
• Assess pain: location, characteristics, radiation.
• Inquire about nausea/vomiting, fever, chills, hematuria.
• Physical assessment includes inspection, auscultation, and palpation of the abdomen, and assessment of the testes and pubic area.
• Examine urinalysis, KUB, ultrasound, or abdominal and pelvic CT results.
• Analyze urine in the strainer for calculi.
• Recognize pain management and address potential fluid volume deficit.

Analysis

• Sudden onset of sharp, severe flank pain radiating to the groin, testicles, or labia indicates a stone.
• Fever and chills suggest systemic infection.
• Hypoactive bowel sounds may be present during abdominal assessment.
• Urinalysis shows leukocytes, bacteria, nitrites, blood, and crystals.
• KUB, ultrasound, and CT show the presence of stones and hydronephrosis.

Planning

• Plan should address symptom management, hydration, treatment for stones, antiemetics, and infection, if present.

Implementation

• Administer analgesics and antiemetics for pain and nausea.
• Provide IV fluids as prescribed.
• Ketorolac and ibuprofen are effective for pain.
• Strain all urine to observe for stone passage.
• Prepare clients for urgent interventions such as lab work or reinforce surgeon instruction.

Evaluation

• Desired outcome: passage of renal calculi resulting in resolved pain.
• Noninvasive methods (hydration, medication, ambulation) are preferred.
• Surgical management may be needed.

Treatments

• Observation is used for stones < 5 mm, which have a 90% chance of passing.
• Strain all urine, and inspect the strainer for stones.
• After resolution, investigate the original cause of development.
• A 24-hr urine sample and basic metabolic panel (BMP) may be ordered for future stone prevention.
• Tamsulosin (Flomax), nifedipine (Procardia), and alfuzosin (Uroxatral) promote stone expulsion by relaxing the ureter.
• Extracorporeal shockwave lithotripsy (ESWL) destroys stones in the kidney and upper ureter.
• Ureteroscopy with laser lithotripsy is used for stones in the lower ureter.
• ESWL is effective for stones < 10 mm and can be used for stones between 10 and 20 mm depending on location and composition.
• Urgent intervention needed for obstructing stone with fever, UTI, or sepsis.
• Clients with only one kidney, obstruction, or stone obstruction with elevated creatinine require urgent treatment.

Medications

• Alpha Blockers: tamsulosin (Flomax) and alfuzosin (Uroxatral) relax bladder neck and prostate.
  • Concurrent use with antihypertensives increases hypotension risk, so instruct clients to change positions slowly.
• Calcium Channel Blocker: nifedipine (Procardia) causes systemic vasodilation.
  • Contraindicated in hypotension.
  • Teach clients to check pulse and report difficulty breathing, swelling, or persistent headache.
• NSAIDs: ketorolac (Toradol) and ibuprofen (Advil) inhibit cyclooxygenase (COX).
  • Take NSAIDs with food or milk to minimize GI upset.

An overview of renal calculi, also known as kidney stones, nephrolithiasis, or urolithiasis, and their formation due to mineral and salt buildup. It covers etiology related to dietary factors like high calcium, oxalate, or sodium, urinary stasis, and inadequate hydration including risk factors.