Complications

CKD is associated with a wide range of complications leading to adverse health outcomes. For some complications, the causal pathway between kidney disease and adverse outcomes is well-known. For these complications, there are clinical practice guidelines for testing and treatment of modifiable factors to prevent adverse outcomes.1

People with CKD are prone to develop a variety of complications which reflect loss of endocrine or exocrine function of the kidneys. The incidence and prevalence of these complications increase with severity of CKD as defined predominantly by GFR categories.1

Note that not all people with CKD will have all of the complications and complications may not occur at the same rate or to the same degree in individuals with the same categories of GFR or albuminuria. Nonetheless knowledge of the common complications and treatment options is important in the care of CKD.1

Anaemia

Anaemia is an important complication of CKD because it contributes significantly to the heavy symptom burden of CKD. It has a major impact on the lives of people with CKD but it is potentially reversible with appropriate treatment.1

CKD metabolic bone disease including laboratory abnormalities

Changes in bone mineral metabolism and alterations in calcium and phosphate homeostasis occur early in the course of CKD and progress as kidney function declines. These changes are grouped under the umbrella term Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) which includes renal osteodystrophy and extraskeletal (vascular) calcification related to abnormalities of bone mineral metabolism.1

Treatment of CKD-MBD:

Disturbances of calcium, phosphate, vitamin D, and PTH develop early during the course of CKD and are associated with adverse outcomes. Studies of these and other markers of bone mineral metabolism have improved our understanding of disease mechanisms governing adverse outcomes of CKD-MBD but clinical studies have yet to indicate whether or not manipulation of these markers improves patient-level outcomes.1

Vitamin D supplementation and bisphosphonates in people with CKD:

The nephrological community suggests not to routinely prescribe vitamin D supplements or vitamin D analogues, and in the absence of suspected or documented deficiency, to suppress elevated PTH concentrations in people with CKD who are not on dialysis.1

Acidosis

The prevalence and severity of metabolic acidosis in people with CKD rises progressively as GFR falls.

Adaptations in acid excretion by the kidneys initially prevent a fall in serum bicarbonate concentration but as GFR continues to decline below 40 ml/min/1.73 m2, metabolic acidosis commonly develops.

The nephrological community suggests that in people with CKD and serum bicarbonate concentrations <22 mmol/l treatment with oral bicarbonate supplementation be given to maintain serum bicarbonate within the normal range, unless contraindicated.1

CKD and cardiovascular disease

People with CKD are considered to be at increased risk for cardiovascular disease. Population-based studies have demonstrated an increased risk of death and cardiovascular mortality as GFR falls below 60 ml/min/1.73 m2 or when albumin is detected on urinalysis. This is not explained by an increase in traditional risk factors. There are CKD-specific risk factors associated with more advanced CKD which drive the high rates of mortality and morbidity even at young ages. People with CKD are more likely to experience a cardiovascular event than to progress to ESRD, have a worse prognosis with higher mortality after acute myocardial infarction (MI), and have a higher risk of recurrent MI, heart failure and sudden cardiac death. Management of modifiable cardiovascular risk factors, such as improved blood pressure and diabetes control, also reduces CKD progression.1

CKD and peripheral arterial disease

There is a strong link between CKD and peripheral arterial disease (PAD). Symptoms of PAD may only be present in a minority of people who have clinical evidence of PAD. It is therefore important to measure ankle-brachial index and perform regular systematic assessment of the lower limbs of people at high risk of PAD to identify bruits, loss of pulses, cool pale extremities, delay in venous filling, and skin ulceration.1