Chronic kidney disease (CKD) describes abnormal kidney function and/or structure. It is common and often exists together with other conditions, such as cardiovascular disease and diabetes.
The 'National service framework for renal services' adopted the US 'National Kidney Foundation kidney disease outcomes quality initiative' (NKF-KDOQI) classification of CKD. This classification divides CKD into 5 stages according to the extent of a person's loss of renal function. Stage 4 CKD is defined by a glomerular filtration rate (GFR) of 15–29 ml/min/1.73 m2, and stage 5 by a GFR of less than 15 ml/min/1.73 m2.
CKD progresses to these more advanced stages in a small, but significant percentage of people. In 2010, the Health Survey for England reported a prevalence of moderate to severe CKD (stages 3 to 5) of 6% in men and 7% in women, as a percentage of the total population in England. CKD stages 4 and 5 were reported at a prevalence of 1% or less. Although this figure might seem small, it translates to a prevalence of up to 520,000 people in England alone.
When CKD stage 5 advances to end-stage renal disease (ESRD), some people progress to renal replacement therapy (RRT). The UK Renal Registry reported that 49,080 adult patients were receiving RRT in the UK at the end of 2009. Of these, 25,796 were receiving RRT in the form of dialysis (a population sometimes classified CKD stage 5D).
As kidney dysfunction advances, there is a higher risk of mortality and some comorbidities become more severe. Hyperphosphataemia is one example of this, and occurs because of insufficient filtering of phosphate from the blood by poorly functioning kidneys. This means that a certain amount of the phosphate does not leave the body in the urine, instead remaining in the blood at abnormally elevated levels.
High serum phosphate levels can directly and indirectly increase parathyroid hormone secretion, leading to the development of secondary hyperparathyroidism. Left untreated, secondary hyperparathyroidism increases morbidity and mortality and may lead to renal bone disease, with people experiencing bone and muscular pain, increased incidence of fracture, abnormalities of bone and joint morphology, and vascular and soft tissue calcification.
For adults with stage 4 or 5 CKD who are not on dialysis, the UK Renal Association guidelines recommend that serum phosphate be maintained at between 0.9 and 1.5 mmol/l. For adults with stage 5 CKD who are on dialysis, it is recommended that serum phosphate levels be maintained at between 1.1 and 1.7 mmol/l. Because of the improved removal of phosphate from the blood through dialysis, adults on dialysis have different recommended levels to those with stage 4 or 5 CKD who are not on dialysis.
For children and young people with stage 4 CKD, the NKF-KDOQI guidelines and European guidelines on the prevention and treatment of renal osteodystrophy recommend that serum phosphate be maintained within age-appropriate limits. For those with stage 5 CKD, including those on dialysis, it is recommended that serum phosphate levels be maintained at between 1.3 and 1.9 mmol/l for those aged 1–12 years, and between 1.1 and 1.8 mmol/l during adolescence.
Standard management of hyperphosphataemia involves the use of both pharmacological and non-pharmacological interventions, as well as the provision of education and support. However, there is wide variation between units and practices across the UK in how these interventions are used. At the end of 2009, data from the UK Renal Registry showed that only 61% of patients receiving haemodialysis and 70% of patients receiving peritoneal dialysis achieved serum phosphate levels within the recommended range. This, together with a rising prevalence of CKD, led to the development of this clinical guideline on the management of hyperphosphataemia.
The guideline will assume that prescribers will use a drug's summary of product characteristics to inform decisions made with individual patients.
This guideline recommends some drugs for indications for which they do not have a UK marketing authorisation at the date of publication, if there is good evidence to support that use. The prescriber should follow relevant professional guidance, taking full responsibility for the decision. The patient (or those with authority to give consent on their behalf) should provide informed consent, which should be documented. See the General Medical Council's Good practice in prescribing and managing medicines and devices for further information. Where recommendations have been made for the use of drugs outside their licensed indications ('off-label use'), these drugs are marked with a footnote in the recommendations.
This document is for healthcare professionals and other staff who care for people with stage 4 or 5 CKD, including those with stage 5 CKD who are on dialysis. This includes primary, secondary and tertiary care settings. Where it refers to children and young people, this applies to all people younger than 18 years. Where it refers to adults, this applies to all people 18 years or older.
 A GFR of over 90 ml/min/1.73 m2 is considered normal unless there is other evidence of kidney disease.
 Note: in this guideline, those who choose not to participate in an active treatment programme for their ESRD (which would generally include RRT, diet, pain management etc), instead opting for 'conservative management', are considered to be a subset of the stage 5 population who are not on dialysis.