The basics - Loin pain

Two important diagnoses are obstructed infected kidney and renal calculi.

Renal calculus which has been passed to the bladder
Renal calculus which has been passed to the bladder

Loin pain is a common presenting symptom in general practice and the potential underlying causes are extensive (see box below). The most common include UTI, renal calculus and musculoskeletal problems.

Acute loin pain
The aetiology of acute loin pain includes causes of general acute abdominal pain but two important diagnoses to consider are an obstructed infected kidney, a potentially life-threatening condition, and renal calculi, where admission may be required to manage the pain.

It is important to take a detailed history of the patient's pain and any associated symptoms, such as fever, rigors, vomiting and lower urinary tract symptoms.

Ask about precipitating and relieving factors, for example, muscular pain is often associated with movement. A patient with renal colic will classically describe severe abrupt exacerbations with a dull ache and restlessness.

The pain may radiate to the groin and testicles or labia majora and urine is usually (85 per cent) dipstick positive for blood. It is important to note drug history and any relevant family history, for example, the risk of renal calculi is doubled in those with a positive family history.

Retroperitoneal fibrosis is associated with bromocriptine, methyldopa, beta-blockers and methysergide. Overuse of analgesia could cause loin pain secondary to papillary necrosis.

Beware of older patients with a history of hypertension, smoking or hypercholesterolaemia who may present with renal colic pain due to a dissecting abdominal aortic aneurysm.

Temperature, pulse and BP should be checked. Urinalysis should be performed to look for red cells, white cells and nitrites.

A full abdominal examination should also be performed, particularly looking for loin tenderness.

If muscular pain is suspected examine the back movements and note if movement exacerbates the pain.

Respiratory and cardiovascular systems examination may also be appropriate depending on the history.

Chronic loin pain
The approach to chronic loin pain is similar and history and examination findings should guide the clinician to the appropriate investigations.

If recurrent renal colic is suspected check local urology guidelines as increasingly IV urography is being superseded by CT urograms.

In patients where contrast studies are contraindicated, consider plain abdominal X-ray and ultrasound scanning. Even if both are normal, up to 40 per cent of renal calculi are not visible on X-ray, so if symptoms persist consider referral to urology.

Consider the possibility of a renal tumour in patients presenting with a gradual onset of persisting pain which may be associated with visible haematuria and a mass.

The diagnosis of chronic kidney pain (also known as loin pain haematuria syndrome) is one of exclusion, normally made in secondary care and may be managed by urologists or the chronic pain team.

Management
UTI/Pyelonephritis

An evaluation of the upper urinary tract should be performed to rule out urinary obstruction or stone disease.1 Investigations such as non-contrast CT should be considered if the patient remains febrile after 72 hours to rule out complicating factors, such as renal tract stones or perinephric abscesses.

Treatment depends on local microbiological resistances and guidelines. In general, a sevenday course of a quinolone antibiotic is recommended in mild cases of pyelonephritis 1. More severe cases should be admitted as a urological emergency.

Consider referral for further investigation of a possible underlying abnormality of the renal tract for men following their first episode of acute pyelonephritis, in women following two episodes and all patients with a UTI due to Proteus species.2

Renal colic
First presentations of renal colic should be referred to the urology service for assessment.3 Acute management consists of analgesia with either NSAIDs (unless contraindicated) or opiates. The addition of alpha blockers can increase the rate of spontaneous stone passage by up to 30 per cent.4

Admission is not necessary for recurrent stone formers or those who have recently had treatment such as extracorporeal shock wave lithotripsy, provided there are no signs of infection or renal impairment and their pain can be adequately controlled with oral analgesia.

These patients should be reviewed in 24-48 hours and if their pain has not resolved, they are feverish or have other signs of sepsis, then they should be referred for admission.

Muscular pain
This should only be diagnosed once a renal or other likely non-musculoskeletal cause of loin pain has been excluded through comprehensive history taking and examination.

Reassurance and simple analgesia may be all that is required but, as with any case of back pain, it is imperative to safety net and advise the patient to return if their symptoms persist or become worse.

  • Dr Porter is a salaried GP in Rochford, Essex
Differential diagnosis of loin pain
Urinary tract causes:
  • UTI
  • Pyelonephritis
  • Renal calculus
  • Infected obstructed kidney
  • Renal tumour
  • Loin pain haematuria syndrome/chronic kidney pain
  • Glomerulonephritis (rare)
  • Polycystic kidney disease (rare)
Other causes:
  • Muscular strain
  • Thoracic/lumbar spine nerve root pain
  • Rib fracture
  • Shingles
  • Dissecting abdominal aortic aneurysms
  • Retroperitoneal fibrosis
  • Pulmonary embolism
  • Pneumonia
  • Diverticulitis
  • Cholecystitis
  • MI

References

1. European Association of Urology (EAU). Guidelines on Urological Infections, 2009.

2. Pyelonephritis-acute, Clinical Knowledge Summaries, 2009.

3. British Association of Urological Surgeons. Guidelines for the Acute Management of First Presentation of Renal/Ureteric Lithiasis, December 2008.

4. EAU. Guidelines on Urolithiasis, 2009.

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Item Code: MINT/PPR-12008

Date of Preparation: May 2012

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