As the GFR declines, symptoms and signs of kidney failure become more common and more severe (see Fig. 4.1). To reflect that, CKD is graded into five stages by eGFR: G1–G5.

Patients with eGFR >60 need to have other evidence of kidney disease, such as proteinuria or a structural abnormality, to qualify as having Stage G1 (eGFR >90) or Stage G2 (eGFR 60–89). Stage G3 is divided into G3a (eGFR 45–60 ml/min/1.73 m²) and G3b (eGFR 30–45). Stage G4 is eGFR 15–29 ml/min/1.73 m² and G5 is eGFR <15 ml/min/1.73 m².

The definition of CKD requires two reduced eGFR readings at least 3 months apart to confirm that the disease is chronic and implications for health to justify the term ‘disease’. The full classification of someone with CKD requires the underlying cause, the eGFR and the level of albuminuria (see Sect. “Proteinuria” in page 143) [1].

Kidney failure does not make you feel very ill until it is advanced, so taking a history from a patient with kidney disease is little help in judging kidney function. The severity of symptoms experienced at a given level of eGFR varies considerably between individuals, some people remaining asymptomatic despite very low function.

The duration of symptoms is not a reliable guide to how quickly kidney failure has developed. Patients with chronic kidney disease may present acutely after a long period of symptomless disease (see Patient 4.1).

As GFR falls below 45 the commonest symptom is fatigue , defined as extreme and persistent tiredness, weakness or exhaustion – either mental, physical or both [2]. Patients whose GFR declines very slowly and are otherwise well may adjust their lifestyle and expectations to their gradually increasing fatigue.

As GFR declines below 20, symptoms such as insomnia , restless legs and itching (uraemic pruritus ) increase.

Restless legs syndrome is a curious unpleasant symptom that patients characteristically find hard to describe. They refer to throbbing, pulling or creeping sensations inside their legs and have an uncontrollable urge to move them. The symptoms are worse when relaxing and are often worst at night. Moving the legs temporarily eases the feeling.

Itching is a major debilitating symptom for some patients with CKD stage G5, both before and after starting dialysis. Its constant presence, especially at night, leads to exhaustion and depression (Patient 4.1). Severe itching is even associated with increased mortality [3].

The itching may be associated with dry skin but there is usually no rash. Constant scratching causes bleeding and scarring (see Figs. 4.3 and 4.4).

The pathophysiology of these symptoms is not fully understood. As they often occur together, it is likely they are mediated by neuronal ‘over activity’ possibly due to the effects of uraemia on the nervous system [4].

Treatment of severe insomnia, restless legs and itching requires careful use of drugs that modify neurotransmission. Gabapentin and pregabalin can be particularly helpful for all these symptoms [5, 6]. The effect of gabapentin on itching is often dramatic, a single tablet switching off the symptom (Patient 4.1 continued). This supports the theory that itch is caused by excessive activity of the nerve fibres that transmit the sensation [7].