referral criteria from primary care - asymptomatic renal tract stones

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Primary care or secondary care management of acute renal colic (1):

  • about 90% of stones that cause renal colic pass spontaneously
  • patients with acute renal colic should be treated with fluids and analgesics (and should strain the urine to recover stone for analysis)
  • often renal colic is a prompt for immediate hospital admission
    • however a review suggested that this condition may be initially managed in primary care and immediate hospital admission is indicated if:
      • highgrade obstruction or failure of oral analgesics to relieve pain may require hospitalization, or,
      • a urinary tract infection in the setting of an obstruction - this is a urologic emergency requiring immediate drainage, usually with a ureteral stent

A review stated (2):

Patients with known urinary stones also require urgent referral if their pain is uncontrolled with oral analgesia, or if they have signs of sepsis.
For patients whose symptoms have settled, less urgent imaging can be requested, as long as there are no other clinical concerns. Renal function should also be checked.

More detailed advice concerning when a patient should be admitted urgently is provided below (1,2,3):

    • patient is in shock or has fever or other signs of systemic infection
    • patient is at increased risk of acute kidney injury, examples when this may occur include:
      • if there is a solitary or transplanted kidney,
      • pre-existing chronic kidney disease, or
      • bilateral obstructing stones are suspected
    • patient is pregnant
    • patient is dehydrated and cannot take oral fluids due to vomiting
    • diagnostic uncertainty
    • if there is no response to symptomatic treatment within 1 hour (or sooner depending on clinical judgement), or there is a rapid recurrence of severe pain
    • consider admission in people over the age of 60 years depending on clinical condition and diagnostic certainty
      • a leaking aortic aneurysm may present with identical symptoms and should always be considered as a differential diagnosis in this age group

  • this guidance suggests that patients who are not admitted should be referred urgently for early investigations - arrange urgent referral to urology within 7 days of the onset of symptoms (if possible) so that diagnostic investigations can be done to confirm the diagnosis and to assess the likelihood of spontaneous stone passage
    • this is vital in order to exclude or treat complete obstruction or other complications. If it is not possible to arrange this, hospital admission may be required
    • patient should be advised to seek urgent medical assistance if they develop fever or rigors, the pain worsens, or they have rapid recurrence of severe pain
    • if managed in the community whilst awaiting specialist assessment:
      • exclude urinary tract infection - dipstick urine, MSU
      • check U+Es - if obstruction then creatinine may be raised - although normal levels do not exclude an obstruction
      • check calcium, phosphate, and urate levels. If the serum calcium level is high (greater than 2.60 mmol/L) (2)
        • possible hyperparathyroidism should be investigated by repeating serum calcium and checking parathyroid hormone levels

When to refer patients with asymptomatic stones (3)

  • upper renal tract stones (and very rarely in the lower tract) may be asymptomatic.
  • indications for referral include:
    • stone size >5 mm (unless the patient agrees to watchful waiting after informed discussion);
    • single kidney;
    • chronic obstruction; and
    • recurrent UTIs

Reference:

  • 1. Wasserstein AG. Nephrolithiasis: acute management and prevention. Dis Mon. 1998 May;44(5):196-213
  • 2. CKS (accessed 22/1/2020). Renal colic - acute.
  • 3. Wilcox CR et al. Kidney stone disease: an update on its management in primary care. BJGP 2020; 70: 205–206.

Last edited 04/2020 and last reviewed 07/2021

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