Download K4.Chronic renal failure for doctors

CHRONIC RENAL FAILURE IN PRIMARY HEALTH CARE for doctors
Chronic renal failure seems to have a higher incidence in poorer communities in the
tropics. There is a possible role for recurrent skin infections by streptococci even
though traditionally these infections were thought not to cause permanent renal damage.
Dehydration in hot climates and inappropriate use of traditional and Western
nephrotoxic drugs may also contribute. In older people CRF is caused by the same risk
factors that cause ischemic heart disease and so CRF is becoming more common in older
people for the same reason that IHD is becoming more common in India.
Is there a screening test? Proteinuria by dipstick testing is not adequately specific for
chronic renal disease, and does not lead to proper effective interventions. In diabetic
people who are at high risk of renal disease, the detection of microalbuminuria may lead
to cost effective interventions using ACE inhibitors. Unfortunately standard dipsticks
are not sensitive enough to detect microalbuminuria. It needs measurement of urine
albumin creatinine ratios. The cost of this measurement is high and if it’s high costs
make a poor person abandon cost-effective treatments in diabetes such as BP control
and blood glucose control, then ACR measurement is counterproductive. Serum
creatinine is not sensitive enough to detect early kidney failure for screening. More than
50% glomerular function is lost before serum creatinine increases. The reduced muscle
bulk of Indian patients makes serum creatinine even less sensitive for screening.
Nevertheless in those at risk of renal disease like diabetics and hypertensive people,
yearly calculation of GFR using creatinine and weight (eGFR) may help if costs are not a
problem. If costs are a problem, eGFR is not worthwhile because prevention of CRF
needs primarily good control of BP more than anything else. By doing unnecessary tests
you might prevent people from at least coming and taking BP tablets. The best choice
for screening for CRF is BP measurement at every patient contact (opportunistic
screening) or population screening.
What are the symptoms?
Remember that chronic renal failure may present suddenly because a recent even minor
insult such as mild dehydration can unmask pre-existing asymptomatic CRF that occurred
over a long time. This acute presentation after a minor illness is common in India where
minor symptoms earlier could have been ignored. In such acute presentations of CRF,
you must exclude acute renal failure without any pre-existing CRF. The only absolute way
is through an ultrasound exam to assess renal size, a skill that is well within the scope of
a family physician to learn and keep up to date.
Other ways of presentation of CRF are
 tiredness or weakness
 dizziness
 breathlessness on effort
 swelling face or legs
 High BP on routine screening: Any person <40 years with incidental increase BP or
those older with anaemia or proteinuria and high BP must have serum creatinine
checked.
Should you look for a cause?
Ultrasound examination to rule out stones and obstruction is essential. Urine microscopy
and if needed culture may reveal infection, which could suggest chronic pyelonephritis or
reflux as a cause of CRF. More likely however infection complicates rather than causes
CRF arising from other causes and may make it progress faster. Renal biopsy is very
expensive and may tell you a prognosis but very rarely leads to treatment that will
change out come. It should not be done routinely.
Management of CRF in resource restricted situations is very difficult, but one need not be
entirely negative. Simple cheap and careful management can keep many people fit for long
periods.
A crucial part of treatment is explaining the illness and objectives of treatment to family
and patient. It will take time and repeated explanation, but you need to explain limitations of
treatment, yet give hope that in some cases there is still useful life. Only then patients may
cooperate with the treatment that has limited benefits. Patients need to be on the follow up
register. The mainstay of treatment is
1. Avoid factors that cause CRF to progress fast:
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High BP: High BP is very serious in CRF and you must lower it if possible to systolic of
110 and diastolic 80 provided there is no major deterioration in CRF. If the person has
diabetes and early CRF ACE inhibitors may help slow progression of CRF more than
other drugs. Renal artery stenosis is a known contraindication to ACE inhibitors but is
rare in poorer communities. Suspect renal artery stenosis only in those likely to have
other risk factors of cardiovascular disease. If using ACEi in CRF recheck serum
creatinine 4 days after starting ACE inhibitors. A greater than 15% rise of serum
creatinine would indicate a need to stop ACE inhibitors. Its best to stop ACEi once CRF
is severe so that eGFR is <30ml/h. Fat soluble beta blockers like propranolol and
calcium channel blockers are first line drugs in those without diabetes or who have
advanced CRF. Diuretics should be added if there is fluid overload, but must not allow
dehydration to occur. Explain to family when diuretics need to be withheld (eg during
diarrhoea). Control of severe hypertension will slow progression of CRF and may even
lead to improvement in renal function.
Stop dehydration! In hot climates, dehydration can rapidly make CRF worse. Patients
with CRF must drink as much water as possible as long as swelling does not occur. This
step is especially important during work in the sun. In late CRF vomiting is a problem
that can rapidly hasten the end in late stages. It is not easy to treat, but metochlorpromide
may help.
Salt restriction: Those with high BP or oedema must restrict salt. Some patients without
high BP or swelling need extra salt (salt losing nephropathy). Salt is permitted once BP is
controlled to a level that allows BP to remain controlled or till swelling occurs.
Diet: There is no need to restrict protein because poor families already have severe
protein restriction and further restriction will cause serious malnutrition. Potassium
restriction may be needed in some people especially those on ACE inhibitors if serum
potassium is high.
Avoid certain drugs: Be careful in choosing drugs in CRF! Major culprits are NSAIDS
and tetracyclines, aminoglycosides.
Know when to seek help Explanation should help those in CRF seek help earlier in minor
illnesses. Your health workers need to know when to refer them. Write down clear
guidelines for referral and treatment of simple illnesses in patient notes.
Look for UTI; Protein leak in CRF makes infection likely. Some infections are silent. Use
the dipstick test to screen for infection- if nitrites and leukocytes are positive infection is
very likely. If only one of these is positive infection is possible. Untreated UTI makes CRF
progress faster.
2. Manage complications
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Anaemia: in CRF anaemia can be due to multiple causes: Iron and folate deficiency can
occur due to poor diet, iron deficiency due to gastritis and the anaemia of CRF due to
erythropoietin deficiency. Measurement of iron, transferrin or ferritin to differentiate
causes is not helpful because ferritin and transferrin levels are markedly affected by CRF
itself. Blood film may show microcytic hypochromic anaemia, but the simplest
intervention is preventive iron and folate supplement (eg macrofolin 1 tab daily or
parenteral iron and oral folate if oral iron is not tolerated. If anaemia still occurs then it
is likely due to erythropoietin deficiency. Erythropoietin injections have markedly
improved quality of life in those with advanced CRF because anaemia can be very
debilitating. The dose can be reduced to 4000U every 4 weeks and still produce
significant rise in haemoglobin, but even this dose is simply expensive.
Renal osteodystrophy: The current sad state of CRF management for those who are poor
is such that most die long before renal osteodystrophy causes problems. Apart from
addition of calcium to the diet, other interventions such as synthetic activated vitamin D
analogues simply increase costs and may drive away patients from taking more
sustainable and important interventions such as BP medications.
Acidosis: People in CRF already need many medications. Routine addition of sodium or
calcium bicarbonate markedly increases the number of tablets and is not useful. Acidosis
in CRF is a late problem when prognosis is poor and when palliative care may be the
best option.
Cardiovascular disease: Many older CRF patients if they survive long develop
cardiovascular (CVS) disease and in Western countries most die of CVS disease.. So
reduce cardiovascular risk by stopping smoking and encouraging healthy diet and
moderate physical activity. Lowering cholesterol with statin tablets like atorvastatin is
expensive but may need to be considered if costs will not put people off from taking BP
medications which are more important.
It is important to be realistic. CRF is difficult to manage end stage without dialysis and
erythropoietin. There comes a time when treatment needs to change from aggressive BP
control etc, to palliative care and symptom control.