This article reviews the key issues to consider when the care of patients with chronic kidney disease (CKD) culminates in the need for dialysis. Beginning dialysis is likely to be a time of major changes in a patient’s care, not least because several common medications become contraindicted.

First and foremost, it’s important to highlight the necessity of a good communication plan between primary care providers and nephrologists for patients on dialysis. Bi-directional communication is vital, and it may help to arrange a formalized framework for shared care.

Overview of hemodialysis (HD)

Most patients receive HD in either a hospital or community-based facility, but some perform hemodialysis in their own home. Key features are:

• HD requires reliable vascular access to the patient’s bloodstream.
• Of the three types of vascular access (arteriovenous (AV) fistula, AV graft, catheter), an AV fistula is preferred due to a lower rate of infection and other complications, more reliable access to the bloodstream, and improved overall patient survival. An AV fistula is usually created at least 3-4 months before HD is required. If your patient has an AV fistula, avoid taking blood pressure measurements on that side.
• Traditional HD occurs for four hours, three times per week. Patients who dialyze at home may dialyze for a longer period, several nights a week.
• Patients on HD have a “dry weight” established, which is meant to represent their euvolemic state (i.e. if the weight is any lower, the patient has unacceptable symptoms of hypotension, cramping, etc. on dialysis). Patients on HD are taught to maintain a modest fluid restriction in between HD sessions and are dialyzed to their “dry weight” each run.

Overview of peritoneal dialysis (PD)

PD is a home-based form of dialysis usually done by the patient or a caregiver. Some points about peritoneal dialysis:

• Patients on PD have a catheter inserted into their abdomen which provides access to the peritoneal cavity. Dialysis solution is instilled into the peritoneal cavity, left for a period of time, and then drained back out, removing toxins and extra fluid when drained out. The filling and draining of the solution is either done manually (i.e. a bag of solution fills and drains using gravity) or with an automated device.
• PD schedules can either be continuous (i.e. fluid in the abdomen all the time) or intermittent (i.e. periods of the day when the abdomen is “empty”). In contrast to hemodialysis PD is usually done 7 days a week.
• Patients on PD are taught to weigh themselves and adjust their PD fluids to maintain a target weight.

When providing primary care for a patient on PD, the following caveats are important to remember:

• Maintaining residual renal function is important, as PD preserves residual renal function (RRF) better than HD, and patients do better if they maintain some of their own native kidney function. Therefore, avoid nephrotoxins such as non-steroidal anti-inflammatory medications, aminoglycosides and IV contrast dye whenever possible.
• PD patients receive a significant glucose load as the PD solution is glucose-based. Up to 60% of this glucose is absorbed, potentially leading to weight gain, hyperlipidemia (especially hypertriglyeceridemia), and hyperglycemia/increased insulin requirements. Insulin can be added to the PD dialysate, so if glycemic control is a concern, talk to the nephrologist.
• Patients on PD often suffer from constipation. Even mild constipation can cause the peritoneal dialysis catheter to malfunction, which often manifests as a failure to drain. Constipation needs treatment as soon as it’s noted. Appropriate agents include suppositories, lactulose, or saline enemas — avoid laxatives that contain magnesium or phosphorus.

Immunizations and malignancy surveillance

Patients on dialysis have a reduced response to vaccination, thought to be due to the immunosuppressive nature of uremia. Despite the reduced response, it’s recommended that patients on dialysis be vaccinated similarly to the general population. In particular, there are several vaccines quite important for the dialysis population.

• Hepatitis B — Patients on hemodialysis are routinely vaccinated against hep B. Because the immune response to hep B vaccination is more predictable at higher levels of GFR, ideally patients who may need hemodialysis are vaccinated before they reach end stage kidney disease. This is often done by the primary care provider.
• Influenza and pneumococcal vaccines — Although less data is available for these vaccines in patients on renal replacement therapy, it’s recommended that they be given as per local immunization guidelines. Remember, however, that the response in patients with renal failure may be less than normal, especially in the maintaining adequate antibody titres over time.
  • Yearly influenza vaccines are recommended in all dialysis patients.
  • Pneumococcal vaccines are recommended in all dialysis patients.
• Tetanus, diphtheria and pertussis vaccines — should also be given as per local immunization guidelines and kept up to date.

In general, age and gender-appropriate malignancy surveillance is recommended for dialysis patients. Because of the shortened life expectancy of people on dialysis, the decision for comprehensive cancer screening must be patient-specific and include considerations of both the patient’s specific cancer risk and the potential eligibility for renal transplantation. Note that dialysis patients may be at high risk of certain cancers such as urological cancers.

Common co-morbidities in patients on dialysis

Cardiovascular disease is the most common cause of death in dialysis patients. However, the approach to treating cardiovascular risk factors in this patient population remains controversial.

• Blood pressure (BP) — Most patients on dialysis are hypertensive. Although the actual method of measuring BP and recommended targets are controversial, one suggestion is a pre-HD blood pressure of < 140/90 and a post-HD blood pressure of < 130/80.
  • Control of volume status is the mainstay of hypertensive treatment for patients on HD. In most dialysis patients, proper volume control can either normalize the BP or make it easier to control. It’s especially helpful in PD patients, as nearly all of them can become normotensive with strict adherence to volume control. Because of the close interplay with volume status, the nephrologist usually does the monitoring and treatment of blood pressure.
• Hyperlipidemia — Most patients on dialysis have abnormalities of lipid metabolism including hypertriglyceridemia, reduced HDL and increased Lp(a). Although it’s well known that patients with CKD are at higher cardiovascular risk, it’s not proven that treating elevated cholesterol in dialysis patients reduces cardiovascular events.
• The results of two recent large randomized controlled studies looking at the effect of lipid lowering with statins in HD patients both found that:
  • Statins are generally well tolerated in HD patients and are effective at decreasing serum cholesterol.
  • However, statins have no effect on cardiovascular endpoints (death from CV causes, non-fatal MI, non-fatal stroke) in HD patients.
  • As a result of the findings of these trials, the role of statin therapy in HD patients is currently unclear and should be addressed on an individual basis.
• The role of statin therapy in patients on PD hasn’t been well studied but it’s often recommended as patients on PD may have a more atherogenic lipid profile due to glucose absorption from the dialysate.

Anemia

• Anemia of CKD is the result of reduced renal erythropoietin production, and to a lesser extent decreased RBC survival. Iron deficiency and increased risk of blood loss exacerbates the anemia of CKD. Almost all patients on dialysis require supplemental iron and erythropoetic stimulating agents (ESAs). Iron is usually given orally if a patient is on PD, and IV if a patient is on HD. Target levels of hemoglobin are generally between 110-120 g/L.
• An acute drop in hemoglobin in dialysis patients on stable doses of iron and ESAs is not normal and should alert the health care provider to assess for causes of anemia as in the general population. Dialysis patients are at increased risks of GI blood loss and this should be evaluated for closely with any acute drop in hemoglobin.

Mineral metabolism

• CKD leads to hyperphosphatemia, hypocalcemia, low activated vitamin D levels and elevated PTH, which is initially appropriate as this will lower phosphate and raise calcium. After time, PTH secretion becomes inappropriate and leads to CKD mineral and bone disease (CKD-MBD). Most patients on dialysis are on supplemental calcium and activated vitamin D.
• Calcium is also often used as a phosphate binder in patients on dialysis. When oral calcium is given at the start of a meal, it acts as an effective and inexpensive phosphate binder. When given between meals or at bedtime, it provides supplemental calcium.
• Patients on dialysis are at risk of osteoporosis in addition to traditional forms of CKD-MBD. However, the following caveats are important to remember:
  • Traditional methods of diagnosing osteoporosis, such as Dual-Energy X-Ray Absorptiometry (DEXA) are unreliable in patients on dialysis and shouldn’t be used.
  • Diagnosing osteoporosis requires exclusion of the other forms of CKD-MBD, which may require specialized biochemical testing or bone biopsy.
  • The role of bisphosphonates for patients on dialysis is unclear and they generally aren’t recommended for this patient population.

Diabetes

• Diabetes in the dialyzed patient is often the province of the general practitioner. Renal failure poses several obstacles in treating diabetes:
  • Biguanides such as metformin must be avoided in dialysis patients due to the risk of lactic acidosis.
  • When using oral hypoglycemics, certain sulfonylureas (e.g. glyburide) should be avoided in renal failure as they have the potential to accumulate. Gliclazide or glipizide, which don’t accumulate, are preferred.
  • When using insulin, insulin requirements will generally decrease as pre-dialysis renal failure progresses (due to decreased insulin degradation). Some patients may even be able to come off insulin when the GFR becomes severely compromised (i.e. < 20mL/min). Once on dialysis, insulin requirements may increase, especially on PD as a significant amount of the glucose used in the dialysis solution is absorbed. Diabetic patients on PD are often taught to inject insulin directly into their PD dialysate.

Depression is common in the dialysis population. In many centres, dialysis patients are followed by a renal social worker, who may provide useful collateral information, both for the nephrologist and the primary care provider. Depression must be distinguished from under-dialysis, as some symptoms (such as anorexia and failure to thrive) can be similar in the two conditions. The pharmacologic treatment of depression is similar to that of the general population and selective serotonin reuptake inhibitors are generally safe.

Conclusion

Given the complex interplay of risk factors, diagnostic markers and drug interactions, it’s easy to see how a lack of communication between primary and specialist carers can produce confusion, or duplication or omission of care services. Yet minimal communication between nephrologist and GP is too often the norm. The patient will be the beneficiary when we agree in advance who is responsible for which aspects of care. This is something all parties should be working to improve.