Nephrolithiasis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Andrea Tamayo Soto [2]

Definition

Nephrolithiasis is the presence of stones, in the kidneys or the ureters, formed by different substances. The common presentation is a severe colic type pain in the abdomen flanks, sometimes including nausea, vomits or even fever.

Causes

Life Threatening Causes

• Renal Obstruction
• Renal Isquaemia
• Renal Impairment

Common Causes

• Hypercalciuria
• Hyperoxaluria
• Hypernatruria
• Hypocitraturia
• Hyperuricosuria
• Cystinuria
• Gout
• Metabolic acidosis
• Previous chemotherapy for Lymphoma and Leukemia
• Urine Infection
• Drug related stones
  • Allopurinol
  • Triamterene
  • Indinavir

Management

Diagnostic Approach

Shown below is an algorithm depicting the diagnostic approach to Nephrolithiasis based on the 2014 Review of the Cleveland Clinic, urological and kidney institute.

Characterize the symptoms: ❑ Abdominal Pain ❑ Colic pain ❑ Irradiated to the lower abdomen and groin ❑ Acute, moderate to severe pain ❑ Urinary urgency ❑ Dysuria ❑ Polyuria ❑ Vomits ❑ Nausea ❑ Malaise ❑ Fever and chills

Obtain a detailed history: ❑ History of kidney stones ❑ Personal and Family ❑ Treatment ❑ Stone analysis ❑ History of UTI or pyelonephritis ❑ Anatomic Features ❑ Horse shoe kidney ❑ Solitary kidney ❑ Obstruction of uteropelvic junction ❑ Previous Kidney or ureteral surgery ❑ Diseases such as: ❑ Hyperparathyroidism ❑ Renal tubular acidosis ❑ Cystinuria ❑ Gout ❑ Diabetes mellitus type 2 or Insulin resistance ❑ Inflammatory bowel disease ❑ Renal insufficiency ❑ Sarcoidosis ❑ Gastro-intestinal pathology ❑ Drug treatments and regular intake: ❑ Carbonic anhydrase inhibitor ❑ Ephedrine ❑ Sulfadiazine ❑ Calcium and Vitamin D

Examine the patient: ❑ Measure the blood pressure ❑ Measure the heart rate ❑ Measure the temperature ❑ Abdomen ❑ Tender ❑ Painful ❑ Obesity

Order labs and tests: ❑ Urinalysis ❑ Microscopic hematuria ❑ Nitrates ❑ Leucocytes ❑ Crystalluria ❑ Hemogram ❑ Complete blood count ❑ Serum electrolytes ❑ Urea ❑ Creatinine ❑ CT ❑ Ultrasound if pregnant ❑ Intravenous Pyelography ❑ 24 hour urine collection analysis ❑ Calcium ❑ Phosphorus ❑ Magnesium ❑ Uric acid ❑ Oxalate

Therapeutic Approach

Shown below is an algorithm depicting the therapeutic approach to Nephrolithiasis:

Initial Management ❑ Hydration ❑ Water (2L/24h) ❑ 0.9% Normal saline ❑ 5% dextrose in water and 0.45% Normal saline ❑ Analgesics ❑ Opioid Narcotics ❑ Codeine / acetaminophen (1 or 2 tablets(5-10mg codeine / 325-500mg acetaminophen)) ❑ Hydrocodone / acetaminophen (5-10mg/4-6hours) ❑ NSAIDs ❑ Diclofenac ❑ Ibuprofen ❑ Ketorolac ❑ Antispasmodics ❑ Alpha-blockers ❑ Doxazosin (4mg/day) ❑ Tamsulosin (0.4mg/day) ❑ Calcium channel blockers ❑ Nifedipine (30mg/day) ❑ Steroids ❑ Corticosteroid

Complications?

No

Yes

Size

Infection

Obstruction

<5mm

>5mm

❑ Broad spectrum antibiotics include coverage for: Gram (-) bacili Gram(+) cocci ❑ Antibacterial treatment should be administer to the results of the urine culture

❑ Ureter Obstruction: decresed glomerular filtration decresed renal blood flow Acute intervention is needed

Spontaneous passage

Elective intervention if the has not passed after 2 - 4 weeks

Intervention

Spontaneous passage

Kidney Stone	Treatment and future prevention
Calcium Oxalate stones	❑Thiazide Diuretics ❑Sodium restriction ❑Calcium supplements ❑Protein intake <30% of TCI ❑Vitamin D (if <30ng/ml)
Calcium Phosphate stones	❑Acidify urine ❑Perform a pregnancy test on women ❑Decrease dietary intake of phosphate
Cystine stones	❑Alkalize urine ❑Cystine-binding agents ❑Decrease methionine intake ❑If measures fail: ❑D-penicillamine OR ❑Tiopronin OR ❑Captopril
Struvite stones	❑Acidify urine ❑Avoid supplementary magnesium ❑Acetohydroxamic acid
Uric acid stones	❑Alkalize urine ❑Allopurinol ❑Reduce protein intake <30% of TCI ❑Reduce or eliminate alcohol intake ❑In patients with diabetes - increase tea and coffee intake

	Indications
Acidify urine	❑Betaine (650mg three times/day with meals) ❑Cranberry juice (16oz/day)
Alkalinize urine	❑Potassium citrate (10-20mEq with meals ❑Calcium citrate (1g/day with meals)

Intervention

Treatment	Indications
Extracorporeal shock wave lithotripsy	❑Renal stones <2cm ❑Ureteral stones <1cm
Uteroscopy	❑Ureteral stones
Ureterorenoscopy	❑Renal stones <2cm
Percutaneous nephrolithotomy	❑Renal Stones >2cm ❑Proximal ureteral stones >1cm

Do´s and Don´ts

===Do´s====

• Perform a metabolic evaluation in patients with risk factors for stone recurrence
  • Family history of nephrolithiasis
  • Presence of biliary stone disease
  • Nephrocalcinosis
  • Stones are formed from cysteine, uric acid or calcium phosphate
  • The patient is a child
• Administer tamsulosin and corticosteroids to help stones pass quicker and with less analgesics.
• Proceed intravenously in patients who are unable to take oral fluids or oral medications and with hypotension.
• Perform

===Don´ts====

• Do not recommend calcium restrictions, as the may increase the urinary oxalate excretion.

References

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