Urinary Calculi

Essentials

• The treatment of an acute attack should be started with an intramuscular or intravenous NSAID, a combination of an analgesic and a spasmolytic, or an opioid at the health care facility that the patient first attends.
• Bacterial culture of urine, chemical screening of urine and plasma creatinine should be done/checked.
• The diagnosis should be confirmed with ultrasonography, in specialized care with CT scan. The vitality of the kidneys should be verified by follow-up.
• Attempts should be made to retrieve the stone by straining urine and to analyze the composition of the stone.
• Careful history taking and basic laboratory tests are indicated after the first attack, already, to lower the risk of recurrence.
• In the case of recurrent urinary calculi, the aim should be to lower the concentration of lithogenic factors (primarily calcium and oxalate) in urine and to increase the urine citrate concentration (citrate prevents the formation of calculi).
• Lifestyle modification is indicated in all patients, the most important change being drinking plenty of liquids so as to make the daily urine excretion 2 litres, at least.

Types of stones and their aetiology

Risk factors

• Low fluid intake
• Animal protein-rich diet
• High salt intake
• Low dietary calcium intake
• Primary hyperparathyroidism, gout, obesity, malabsorption (e.g. small bowel resection in association with bariatric surgery)
• Excessive sucrose or fructose intake
• High-dose vitamin C and D supplementation; certain drugs (e.g. sulfa, topiramate, indinavir)

Symptoms and findings

• Most common in middle-aged men
• Intense, colicky pain radiates from the costal arch obliquely to the lower abdomen, groins, and genitals. Pain during urination is common if the stone is in the distal ureter.
• Nausea and vomiting is common.
• Microscopic, or rarely macroscopic, haematuria in 90%
• History showing earlier episodes and cases in the family. Tendency for recurrences is 50% in 10 years.
• Tenderness of the kidneys on percussion may be observed.
• The patient has difficulty keeping still (in contrast to e.g. peritonitis where the patient prefers to lie still).
• Most stones (75-90%) are radio-opaque but urate stones are typically radiolucent and therefore invisible, while cystine stones do not show up well on x-rays.
• Small stones are poorly visible in plain x-rays.
• Renal calculus may cause chronic back pain and infections.

Differential diagnosis

• Colon-related pain (e.g. diverticulitis) Functional Bowel Disorders and the Irritable Bowel Syndrome (IBS)
• Appendicitis Acute Appendicitis
• Biliary or other upper abdominal attacks Cholelithiasis
• Aortic aneurysm Aortic Aneurysm and Dissection
• Gynaecological infections Lower Abdominal Pain of Gynaecological Origin
• Testis torsion Testis Pain
• Renal infarction (N.B. not visible in plain CT examination)

First aid for an attack Dipyrone for Acute Renal Colic Pain, Nsaids Versus Opioids and Non-Opioids for Acute Renal Colic, Fluids and Diuretics for Acute Ureteric Colic

• NSAIDNsaids in Acute Renal Colic intravenously Different Routes of Administration of Non-Steroidal Anti-Inflammatory Drugs (most rapid relief) or i.m. (slower onset of action), e.g.
  • diclofenac 75 mg i.m. or by slow i.v. infusion (> 30 min)
  • ketoprofen 50-100 mg i.m. or 100-200 mg by slow i.v. infusion (> 30 min)
• Combination of an analgesic and a spasmolytic intravenously
  • metamizole sodium and pitofenone hydrochloride (remember the risk of agranulocytosis associated with metamizole)
• Opioid
  • oxycodone 5 mg or 10 mg intramuscularly

Workup

Conservative treatment

• Fluid intake should be increased to make the daily urine excretion 2 litres or more http://www.dynamed.com/condition/nephrolithiasis-in-adults-24#FLUID_AND_ELECTROLYTES.
  • Water, primarily, should be drunk at regular intervals throughout the day.
• Animal protein intake should be reduced.
• Salt intake should be reduced. The 24-h urine Na target is no higher than 80-100 mmol (85 mmol being equivalent to a salt intake of 5 g/day).
• Sucrose and fructose intake should be reduced.
• More vegetables and fruit should be eaten.
• In patients with calcium oxalate stones and/or hyperoxaluria (oxalate >0.5 mmol in 24-h urine), vitamin C supplementation should be avoided, oxalate intake should be restricted and food high in oxalate (such as spinach, potatoes, rhubarb, nuts, almonds) should be avoided.
• Dietary counselling by a dietitian
• Dietary calcium intake should be normal, 800-1 200 mg/day.
  • Calcium restriction will increase the absorption of oxalate from the alimentary tract, predisposing the patient to recurrent urinary calculi.
• For hyperuricaemia, a gout diet should be followed and allopurinol given, as necessary.
• Any condition causing hypercalciuria (such as primary hyperparathyroidism, sarcoidosis, hypervitaminosis D) should be treated.
• A thiazide diuretic reducing calcium excretion is often added to the treatment of idiopathic hypercalciuria (important to preserve normokalaemia, as hypokalaemia reduces citrate excretion).
• In hypocitraturia, urine should be alkalized primarily with 1 080 mg potassium citrate (Acalka^® , 1-2 tablets 2-3 times daily with meals) or, secondarily, with sodium bicarbonate (1 500 mg 3 times daily).
• The aim of the intervention is to correct any abnormalities observed in initial tests (e.g. low urine volume, hypercalciuria, hyperoxaluria and/or hypocitraturia) http://www.dynamed.com/condition/nephrolithiasis-in-adults-24#PREVENTION_OF_STONE_RECURRENCE. Response to the intervention should be assessed in 2-3 months and subsequently according to clinical need, once a year, for example.
• Urine should not be alkalized if the stone consists primarily of calcium phosphate or struvite, because alkalizing might in that case aggravate the disease.
• Any urinary tract infection should be treated as indicated by resistance testing. Follow-up examinations are indicated and prophylactic medication Urinary Tract Infections is usually necessary for patients with infection stones.

Surgical management