Quiz feedback: Chronic kidney disease and oral health

GP panel:

Working out the specific stage of kidney disease for a patient is not something that many GPs have been used to doing on a regular basis. However it was agreed that it provides a useful guide as to when to refer.

The panel decided that this patient was at CKD Stage 2, however they felt that to label a patient at a particular stage was often of little clinical relevance in general practice and that an overall assessment of the whole clinical picture over time was more useful. They felt that the rate of decline is the key – “It’s not which station you are at, but which station you are going to that is important”.

It is worth re-emphasising two points from the article:

1. The confirmation of a new CKD stage is based on a minimum of two eGFR values taken over three months (therefore taking into account variation over time)
2. For a newly diagnosed patient the rate of decline should be established.

How important is it to grade the stage of CKD in a general practice setting?

Specialist comment:

I would agree with the panel, that the overall assessment of the clinical picture is important. Stage 2 CKD (GFR = 85 mL/min) in a 25 year-old male with heavy proteinuria carries a completely different connotation to a 65 year-old male with atherosclerotic vascular disease, no proteinuria and stage 2 CKD (GFR = 68 mL/min).

Urinalysis is always important in the assessment of CKD, especially the extent of proteinuria.

eGFR is inaccurate above a value of 65 mL/min. The aim of the eGFR is to remind practitioners that plasma creatinine is inaccurate in assessing the severity of renal disease. An isolated value has limited value unless it is clearly elevated. The change over time is important.

GP panel:

The first statement is false as only a small proportion of patients with CKD progress to end-stage renal disease, although it is more prevalent among Maori and Pacific peoples.

The panel agreed that they now rely on eGFR results rather than serum creatinine, although acknowledged that experience with its use will vary amongst GPs because it is still a relatively new concept.

It was felt that the requirement for a yearly urinalysis for all people with CKD is difficult to achieve in a “real world” setting. The panel wondered if this is really necessary. There was perhaps some confusion about whether urinalysis meant urine dipstick testing or analysis of a sample sent to the lab. They commented that screening patients with urine dipstick testing is time consuming and often difficult to fit in during a busy consulting session. Ticking a box on a form is quicker and easier but more expensive.

The panel agreed that they would be more likely to check urine in people with declining or low eGFR values than in patients who were stable, with blood pressure and risk factors well managed. The panel queried whether, in these stable patients, the presence of protein in the urine would change management?

They would be interested in some guidance from the specialist about the exact requirements for urine testing and how this may then change management.

In addition, for a sample sent to the lab, should protein/creatinine or albumin/creatinine be requested?

Specialist comment:

This question and the comments from the panel raise a number of important points:

Proteinuria is a very important marker of CKD and also a very important prognostic indicator both for outcome and therapy. CKD with proteinuria is more likely to progress.

Proteinuria is also an independent cardiovascular risk factor. In people with hypertension the presence of proteinuria equates to six to ten fold higher risk of a cardiovascular event (even in the presence of normal renal function). Therefore urinalysis and quantifying proteinuria if present is an essential part of the initial cardiovascular risk assessment in a person with hypertension.

Therapeutic intervention and renal protection aims to lower proteinuria as much as possible. Therefore surveillance of proteinuria provides good feedback about the effectiveness of therapy. A reduction of proteinuria equates to increased renal protection even in the setting of a normal blood pressure.

Urinalysis using a dipstick is an important screening test that I would rate equivalent to taking the patients blood pressure and their weight. It could be performed by the practice nurse whilst the patient is waiting to be seen. In many cases it is a matter of educating the patients that this is part of their annual assessment and if they have this expectation, it should not be too difficult to manage.

There has to be a significant amount of albumin and/or other proteins in the urine before the dipstick is positive (approximately 120 mg/L protein). The absence of dipstick positive proteinuria is very reassuring with respect to CKD and its progression as well as assessing cardiovascular risk. It also means that it is unnecessary to send the urine off to the lab for quantification. If the urinalysis is negative then I would only reassess if there was a significant deterioration in renal function and/or blood pressure control.

The protein/creatinine ratio is the simplest way to monitor proteinuria if present. The first morning specimen is preferable as it has the least variability. The presence of proteinuria will have an impact upon the targets for blood pressure lowering as discussed in Question 5.

The protein/creatinine ratio is different to the albumin/creatinine ratio. The albumin/creatinine ratio is far more sensitive. An elevated albumin excretion rate is recognised as an important marker of endothelial dysfunction in general. It can be elevated in the presence of hypertension, obesity, or following exercise. Again it must be assessed in the clinical context and not in isolation.

GP panel:

The panel agreed that, according to the article, blood glucose is the component that is not necessary in a kidney health check. However they argue that in reality it should be, and in practice often is!  A kidney health check, in a general practice setting, is unlikely to be done in isolation, rather it is done as an extension of a cardiovascular risk assessment or a general health check. In addition, diabetes and renal disease often co-exist.

Specialist comment:

I agree with the panel - a kidney health check should not be done in isolation. Logically it should be part of a cardiovascular risk assessment as CKD is the highest risk factor for cardiac disease. Given the very high prevalence of type 2 diabetes mellitus and the metabolic syndrome in our community, this is the major aetiology of CKD and therefore needs to be screened for. Thus a fasting blood glucose in an at-risk individual may well be part of a cardiovascular/kidney screen.

GP panel:

The panel correctly identified that an eGFR of < 15 mL/min and hyperkalaemia > 7 mmol/L were red flags for urgent same day referral in a patient with CKD.

In addition, the panel felt that some patients with renal colic may also require urgent referral. Although renal colic was not classified as a red flag in the CKD article, it should be acknowledged that in certain circumstances urgent same day referral may be required. The decision to refer would depend on specific patient factors such as pain control, certainty of diagnosis and past history.

The panel concluded that referral is dependent on complex factors and should be decided on a case by case basis.

Specialist comment:

I agree with the panel that an acute deterioration in renal function should prompt an urgent referral. However the exact level is not important, but rather the rapidity of decline. I would not wait until the eGFR was below 15 mL/min in an individual who previously had had normal renal function.

The presence of a rapidly declining eGFR raises the possibility of a rapidly progressive glomerulonephritis and the sooner it is diagnosed and treatment commenced the greater the possibility of reversibility. Clearly an urgent urinalysis is part of this assessment. The presence of proteinuria and or haematuria increases the probability of an acute glomerulonephritis.

The presence of hyperkalaemia is also clearly an indication for acute referral.

If there is any uncertainly I would strongly recommend direct telephone consultation with your local nephrologist.

GP panel:

There is some ambiguity about the ideal blood pressure target for people with CKD particularly those who also have proteinuria or diabetes . The NZGG Cardiovascular Guidelines (2009) state that the target should be <125/75 mmHg for people with diabetes and overt nephropathy, microalbuminuria or other renal disease, or CKD and significant albuminuria. Elsewhere in the document it recommends the same target for all people with CKD in general. The Kidney Health New Zealand Summary Guide recommends the blood pressure target for people with CKD should be <130/80 mmHg and <125/75 if Proteinuria is present. Can the specialist clarify this?

Many people may have been surprised about the level of dietary salt intake that is recommended for patients with CKD – 80 mmol/day which is equivalent to only around one teaspoon of salt. The panel felt that it was useful to have a number to work with as it is difficult to find information for patients on how much salt they should have. They also wondered how to judge how much salt is being consumed as it is often hidden in food.

They queried whether people with hypertension should also aim for a salt intake of less than one teaspoon per day?

There was some discussion about the rationale for salt restriction in elderly people who are often hyponatraemic. The panel queried whether it is unwise to recommend a reduced salt diet in these people?

The panel felt they had a good understanding of the concept of adjusting drug doses in renal failure, however commented that in practice this is sometimes difficult to do on a consistent basis. Setting up a recall for an annual medication review in CKD patients is recommended.

GPs generally tend to be timid with the dose of ACE inhibitors particularly in elderly people. How do you judge what dose is sufficient? The panel would be interested in whether the dose of ACE inhibitor should be increased even if blood pressure is well controlled? What are the benefits of this?

Specialist comment:

The first point I would make is that the recommendations for blood pressure should not be seen as a target. Rather they should be seen as the minimum blood pressure to be achieved, if possible. Essentially the lower the blood pressure the better the outcome. This clearly has to be assessed in the context of the individual. In an elderly patient with long standing isolated systolic hypertension and CKD stage 3, dropping their blood pressure to below 130 systolic may well precipitate a hypotensive fall and a subsequent hip fracture.

The presence of proteinuria and/or albuminuria increases the cardiovascular risk as well as the likelihood of renal progression. A lower blood pressure is advantageous as this is usually associated with a reduction in proteinuria.

There are numerous clinical studies demonstrating the advantages of angiotensin converting enzyme inhibitors or angiotensin receptor blocking agents in reducing proteinuria and improving renal outcomes. Most studies support titrating the dose to the maximum possible dose that can be tolerated to achieve the best outcomes.

ACEI are not contraindicated in elderly people, just as renal artery stenosis is not an absolute contraindication for the use of ACEI. Rather it is a question of caution and careful titration of the dose according to response. If the individual is already on a diuretic then reduction in the diuretic dose or stopping the diuretic as the ACEI is introduced may well be appropriate.

From an epidemiological perspective, increased dietary salt intake is clearly associated with increased hypertension and cardiovascular risk. The WHO recommended daily intake of sodium is 80 mmol/day. In people with hypertension, a reduction in salt intake down to this level can achieve a reduction in systolic blood pressure of about 8 – 10 mmHg (similar to a single anti-hypertensive agent). It should therefore be part of the diet and lifestyle recommendations given to all people with hypertension. With progressive kidney disease the impact of salt and hypertension becomes even more significant with over 90% of individuals with CKD 4 and 5 (pre-dialysis) being very salt sensitive.

The majority of our dietary salt intake is derived from processed food. The amount added at the table probably accounts for only 10%. The National Heart Foundation is working closely with the Food Industry in order to reduce the amount of salt added to food. This has to be done in a controlled manner with a gradual reduction over time so as not to cause major consumer resistance. This has already been successfully implemented in the UK. The best approach to assessing dietary salt intake as well as providing education is to refer the patient to a dietitian.

With respect to elderly people, in most cases hyponatraemia is not due to salt restriction or depletion. Low plasma sodium does not usually mean low total body salt. In most cases it is excessive water retention due to impaired free water clearance, impaired cardiac function etc. Impaired free water clearance is commonly associated with thiazide diuretics and non steroidal anti-inflammatory drugs. Stopping the thiazide and introducing an ACEI is more likely to correct the hyponatraemia in an elderly person who is hypertensive and initially on a thiazide.

Final word

GP Panel

The panel would like to ask the specialist what sort of cases he sees referred by GPs? Does he have any key advice for managing CKD in general practice?

Specialist comment

In our practice we are happy to review any patient who has evidence of kidney disease, when advice with respect to management and investigation is requested. Unless it is an urgent referral, we would request that there are several checks of renal function: plasma creatinine and eGFR, urinalysis and if proteinuria is present a protein creatinine ratio; along with documentation of blood pressure and associated cardiovascular disease and medication.

The control of blood pressure remains the most important part of management of CKD. Therefore assessment of this and attempts to achieve the lowest tolerated blood pressure is important. For example in a 65 year-old with a eGFR of 40 mL/min secondary to hypertensive nephrosclerosis, if blood pressure is well controlled the decline in eGFR may be reduced to < 1 mL/min/year. In this case it is unlikely the individual will process to ESKD (it will take 30 years to reach an eGFR of 10 mL/min).

GP panel:

Halitosis may be associated with some medical conditions including tonsillitis, diabetes and respiratory infections. The panel felt that most GPs find it difficult to broach the topic of bad breath. If it is obvious that a patient has poor oral hygiene, they would generally recommend dental care, however in reality, often bad breath is ignored. They felt that in some situations the problem of halitosis could be raised, particularly if infection or diabetes was suspected. The panel said that they would then test blood glucose but not necessarily use the breath symptom as an explanation of why they were doing this.

Is there an easy way to discuss halitosis with a patient?

How often is halitosis a symptom of an underlying medical condition as opposed to a symptom of poor oral hygiene?

Specialist comment:

How to raise the issue of halitosis is difficult and often one has to “get to know” one’s patient before this subject can be broached. It is easier to broach if information is given at the same time to help the patient realise that it is something that needs investigated to enable management, rather than something that they have to live with.

Halitosis is a common complaint amongst adult dental patients (more uncommon in children). Prevalence is uncertain but has been reported to be 50% of the adult population. The problem with recording this is one of reporting (how many people with bad breath complain of it, and how many people who think they may have bad breath truly have it? Does “morning breath” count? ). Also creating a standard method of measuring halitosis is complex.

Day-to-day, most halitosis is related to smoking, alcohol, caffeine and consumption of certain foods (like garlic).

A New Zealand review* suggested 90% of halitosis cases are due to oral complaints (gingivitis, periodontitis, dry mouth, abscess), and the remainder due to non-oral/ general medical complaints.

* Ayers KM, Colquhoun AN. Halitosis: causes, diagnosis and treatment. N Z Dent J 1998;94(418):156-60.

GP panel:

The GPs on the panel would all be reluctant to lance a dental abscess and their usual practice would be to prescribe antibiotics and pain relief and refer the patient to their dentist. They felt that patients generally only seek dental treatment from their GP after hours or if they cannot afford dental care.

In general practice, amoxicillin clavulanate is reserved for specific indications only, due to issues with bacterial resistance. Amoxicillin or metronidazole is recommended because they will cover most organisms and bacterial resistance is less of an issue.

Do dentists regularly prescribe antibiotics for abscess and if so, do they use amoxicillin clavulanate, or amoxicillin and/or metronidazole?

Specialist comment:

Dentists do prescribe antibiotics, mostly amoxicillin for dental pulp or periodontal abscess or metronidazole for pericoronitis. Because the therapeutic value of antibiotics in many dental situations is debatable, and to minimise the risk of development of resistant micro-organisms, antibiotics are usually reserved for cases of acute cellulitis, or acute dental abscess when there is fever and malaise. However, some reviews have suggested there is still too much prescribing of antibiotics in general dental practice.

Patients often think that the antibiotics will treat the problem and are surprised when an abscess recurs. Abscessed teeth require either extraction, or pulp removal/root canal treatment, or periodontal therapy if the source of the abscess is periodontal.

For a well localised chronic abscess with purulent swelling adjacent to an offending tooth, or draining sinus, then antibiotics are not indicated.

GP panel:

Antibiotics are not indicated for the treatment of toothaches without abscess. The panel did not feel very confident about managing dental problems and would like to have a greater knowledge of what they should be looking for, when examining the mouth. They would like to know if the specialist has any advice about “key points” of a mouth exam in both a child and adult. Usually the people seen with dental problems in general practice are those who cannot afford dental care and who often have poor oral hygiene.

Specialist comment:

Key points that I would suggest for a mouth exam:

• Is the face symmetrical? If not, is this due to swelling?
• Is there limited mouth opening? If so, this can be due to infection (often occurs with pericoronitis around a partly erupted wisdom tooth). Very limited mouth opening is a serious condition.
• Is there evidence of fever?

• Check soft tissues (buccal and lingual): are they pink with no swelling?
• Is there any purulent discharge from any red areas or swellings? In children swellings and sinuses are close to the gum margin. In adults these are more apical (i.e. farther from the gum margin) and often in unattached gingivae.
• Are the soft tissues moist? If they are very dry, there could be a salivary flow problem or dehydration (or the patient may be very anxious)

• Check for occlusion. Can the patient close their teeth together? (important to check for in cases of trauma)
• Is there any mobility of the teeth? In adults mobility is usually indicative of pathology (in children remember there can be physiological mobility).
• Are there any obvious holes or odd coloured teeth (shadowed enamel can be greyish/pinkish and can be due to decay in the underlying dentine)

GP panel:

In general, the respondents did not answer this question very well. Some of this could be attributed to question comprehension, however it appears that there is a lack of knowledge about oral health. Powered toothbrushes are more effective at removing plaque so should be used where possible. Children can use regular strength toothpaste, just a smaller amount. Chlorhexidine mouthwash does reduce oral bacteria count but it should not be used daily as it can stain the teeth and tongue.

Oral hygiene is not an area that a GP would generally approach with a patient. Is this the GPs role or would this be better addressed in a public health forum? GPs tend to rely on dental care services, practice nurses and Plunket nurses to address these issues. The panel felt that to proactively look for dental problems would be fulfilling a doctor agenda rather than a patient agenda. Oral health is assigned a lower priority when weighing up all the other healthcare needs to discuss within a consultation.

Specialist comment:

I can understand oral health being less prioritised, depending on the situation. However oral health is an important part of overall health, and cannot be seen as separate from general health. Improved oral health is a valuable goal, and it is an important part of the message we give to patients to reduce the burden of chronic diseases like dental decay and periodontal disease. For example, we encourage our patients to eat a healthy diet but it is difficult to do so without a comfortable mouth.

There is increasing evidence of a link between poor oral health and systemic disease, however the mechanisms are not clear and to some degree common risk factors are likely to be important.

Should you pro-actively look for dental problems? I would love it if the mouth was included in the examination where possible - for example check that children are enrolled for free dental care or receiving dental care privately, look for white spots on the front teeth or holes in the back teeth as part of a throat examination. A “lift the lip” examination by practice nurses could be done at the same time as immunisation.

In adults part of the problem is the lack of funding for non-acute dental problems in low-income groups. It makes access very difficult and some people just cannot afford to have routine treatment. Supporting early prevention is the key.

GP panel:

Fluoride tablets may be considered for children aged over three years, living in areas without a fully fluoridated water supply. The GPs on the panel could not recall ever prescribing fluoride tablets, in fact some did not know that they could. There is concern that anti-fluoride lobbying is resulting in more and more areas without fluoride and GPs will need to be proactive in ensuring that children meet their fluoride needs and encouraging parents to use fluoride supplements for children. Is this the GPs responsibility?

Specialist comment:

Fluoride tablets are not considered a public health measure, and are recommended only for those considered at risk from tooth decay (risk factors for tooth decay include poor maternal oral health, low socioeconomic status, “grazing” dietary habit, not brushing the teeth with a fluoride toothpaste).

GPs could recommend that parents discuss giving fluoride tablets to their children with a dental health professional. Practice nurses could also discuss this at the time of immunisations. Guidelines recommend that making up fluoridated drinking water is the ideal way to deliver fluoride tablets. Two 1.1 mg sodium fluoride tablets are added to one litre of water to make fluoridated water at 1 ppm