When to refer to the renal unit

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These guidelines have been developed in the Edinburgh renal unit, based on review of evidence in CKD guidelines and from other sources. This guide is ordered by urgency. To read guidance ordered by problem, see the menu on the left or GPinfo home.  Questions not answered?  GPs local to Edinburgh can use our email advice service.

Immediate referral
Suspected acute renal failure (ARF)

  • rapid and significant decline of renal function (unexplained >30% and continuing rise in creatinine) over days to weeks. The faster the rise the more urgent. Sometimes the explanation is obvious and reversible, and immediate referral is not indicated if this can be corrected – e.g. correction of dehydration caused by disease or drugs, known side-effects of drugs.
  • oliguria/anuria with renal impairment not caused by bladder outlet obstruction
  • Where obstruction is known to be the cause, urological referral is usually more appropriate unless biochemical disturbance is life threatening (e.g. severe hyperkalaemia or acidosis)

Acute renal failure superimposed on chronic renal failure – as for ARF

Severe renal failure (GFR<15mls/min; stage 5) that is new or symptomatic. Explain stages – explain how to estimate GFR

  • There may be exceptions for whom careful discussion is indicated rather than immediate referral; e.g. severe associated illness with short prognosis. Discussion is often still appropriate.

Malignant hypertension – severe hypertension with retinal haemorrhages/ exudates; often with renal impairment and dipstick urine abnormalities. More info on malignant hypertension (patient information from EdRenINFO).

 

Urgent outpatient referral
Nephrotic syndrome – urinary protein/creatinine >300mg/mmol with low serum albumin and oedema.

New advanced renal failure – GFR <15mls/min and asymptomatic, or GFR 15-30mls/min. Explain how to estimate GFR

Multisystem disease with evidence of progressive renal involvement

  • renal dysfunction (progressive renal dysfunction should lead to immediate referral, see above) or
  • worsening urinary abnormalities or
  • deteriorating clinical picture

Common diseases here include very treatable conditions such as systemic vasculitis (more info) and renal lupus (more info), though the differential diagnosis is wide and can include infections and malignancies.

Haematuria with proteinuria and worsening renal function – high probability of inflammatory and potentially treatable disease. Some instances will be unrecognised systemic disease.

Hyperkalaemia – dangerous hyperkalaemia in a patient not known to renal services should usually be acutely managed by acute medical team. If severe hyperkalaemia is persistent, renal or endocrine review may be appropriate.
Routine outpatient referral
Declining renal function – e.g. 20% rise in serum creatinine or 15% fall in GFR over 6-12 months or longer, without obvious reversible features.

Known multisystem disease with minor and/or stable renal involvement

  • refer urgently if investigations may establish or alter diagnosis

Suspected renal artery stenosis – for example,

  • acute rise in creatinine of >20% associated with ACE inhibitors or Angiotensin receptor blockers (ARBs) – see How to start an ACE inhibitor
  • recurrent pulmonary oedema in the absence of severe cardiac disease with clinical suspicion of renal artery stenosis

Stable, severe renal impairment with GFR 15-30mls (Stage 4 – explain stages – explain how to estimate GFR) – unless it is clear that the prognosis from other disease is short. A GFR of 30 corresponds to creatinine approx 240 micromol/l in a 30y man, but 160 in a 70y woman.

Moderately severe renal impairment with complications: (stage 3, GFR 30-60) with severe acidosis, disturbances of calcium, phosphate, or high parathyroid hormone. See guideline on management of CKD – stage 3Moderately severe renal impairment with haematuria – GFR 30-60mls/min, (Stage 3 – explain stages – explain how to estimate GFR) – increased likelihood of inflammatory disease. Haematuria 2+ or more.

Proteinuria with haematuria – high probability of underlying renal disease. See guideline on proteinuria.

Isolated proteinuria – if protein/creatinine ratio >200mg/mmol, approx equivalent to 2g/day, without nephrotic syndrome. See guideline on proteinuria.

  • Interpret with discretion in patients with serious comorbidity. Safe to monitor renal function and proteinuria and refer if deteriorates.

Macroscopic haematuria that is urologically unexplained. See guideline on macroscopic haematuria

Diabetes where progression out of keeping with disease (rapidity; no other microvascular complications, particularly retinopathy). Otherwise refer to nephrologist as for other patients with renal disease. See guideline on management of CKD – diabetes

Possible familial renal disease – for diagnosis or advice. Subsequent monitoring may not need to be at a renal unit.

Recurrent renal stones – nephrological and specialist dietetic review is valuable for multiple stone formers. More (brief) info from the EdRen Handbook.

Refractory hypertension (e.g. >150/90 despite agents from 4 complementary classes) if renal disease or renal artery stenosis is suspected.
Management in general practice
GP care, with nephrological advice by email or telephone if necessary, is entirely appropriate for:

Isolated microscopic haematuria (no hypertension or proteinuria) – see guideline on microscopic haematuria.

Isolated proteinuria – protein creatinine ratio <100mg/mmol in the absence of renal impairment or severe hypertension. See guideline on proteinuria.

Mild to moderately reduced GFR – stages 1 to 3 without other features above. Common but important – see guideline on management of patients with reduced GFR

Urinary tract infections without chronic kidney disease. UTIs are very common. Nephrologists rarely have unusual insights into the management of recurrent uncomplicated UTI. See teaching information on UTI and related topics; and patient information on UTIs.
Helpful and essential information when referring
The kidney problem

  • How discovered
  • Any urinary symptoms now or previously

Medical history

  • All significant illnesses
  • Historical recordings of blood pressure and urine dipsticks (including pregnancy and insurance and other medical examinations) can be very helpful
  • Risk factors/lifestyle including tobacco, alcohol

Drug history

  • All current drugs, and any others taken during the period before and since the renal problem is thought to have developed.

Blood tests

  • Tabular results of previous estimations of renal function – unless you are sure the clinician can easily get this from hospital information system at the time of the consultation
  • A series extending to tests where creatinine <100micromol/l if possible
  • Hb, albumin, calcium, phosphate, cholesterol

Urine dipstick results

  • If proteinuria present, quantitation of protein/creatinine ratio is valuable

Blood pressure

  • Recent and historical values on or off treatment

Imaging

  • Renal ultrasound is can reliably exclude obstruction, and show renal size (helpful in distinguishing acute/chronic). CT and MRI investigations may also give useful information if performed. Availability of imaging at first visit is likely to speed conclusions from the referral.
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