Assessment of people with newly diagnosed CKD
Aetiology
The leading causes of CKD in the UK include:
- Diabetes
- Hypertension
- Renovascular disease
- Heart failure (cardio-renal syndrome)
- Inherited renal diseases
- Glomerulonephritis
- Obstructive nephropathy
- Reflux nephropathy
History and Examination
A good history can help to establish the likely aetiology of CKD
Keep the two leading causes of CKD in the UK, diabetes and hypertension, in mind initially.
- Clarify the presence or absence of these risk factors, and if present establish the likelihood that they have contributed to development of CKD.
- This should include questions about the duration of disease and historic glycaemic and blood pressure control.
- In diabetic patients, nephropathy is more likely when other microvascular complications are present.
- A history of retinopathy (especially proliferative diabetic retinopathy requiring laser treatment), peripheral neuropathy or diabetic foot disease should be explored.
Other possible causes of CKD:
- Renovascular disease may be suspected in patients known to have peripheral vascular disease, and cardio-renal syndrome in those with moderate to severe or decompensated heart failure.
- Glomerulonephritis should be considered if there is a history of autoimmune disease or systemic symptoms, for examples rashes, joint pain or swelling, ENT symptoms, respiratory symptoms, or fever.
- Myeloma is an important but under-recognised cause of renal impairment, particularly in the elderly, and a history of back pain may be suggestive.
- Prostatic symptoms in males such as poor urinary stream, nocturia or a sensation of incomplete bladder emptying may raise suspicion of bladder outflow tract obstruction.
- Bladder or gynaecological cancers, including associated pelvic surgery or radiotherapy, are additional risk factors for urinary tract obstruction.
- Reflux nephropathy occurs in patients with a history of recurrent childhood urinary tract infections (UTIs) and enuresis.
Drug history:
- Medications may be implicated in the development of renal impairment and a detailed drug history is essential.
- Establish current or previous use of NSAIDs, lithium, herbal preparations, and illicit substances, including duration and frequency of use.
Family history:
- It is important to identify any family history of kidney disease.
- In cases of autosomal dominant polycystic kidney disease, it is helpful to know details of disease presentation and progression in relatives and any history of intracerebral haemorrhage or sudden death, as the clinical phenotype of disease can vary.
- If the exact nature of familial kidney disease is unknown the pattern of inheritance may give some clues, for example X-linked inheritance is seen in most cases of Alport syndrome.
Complications of CKD:
- The history should also seek to explore any complications of CKD, for example fluid overload, symptomatic anaemia, fatigue, and loss of appetite.
Examination should focus on:
- Determining the aetiology of CKD, which may include diabetic foot or eye complications, renal bruits, palpable polycystic kidneys or hepatomegaly secondary to liver cysts, a palpable bladder, or signs of systemic disease such as rashes or joint swelling.
- Looking for complications of CKD, such as pulmonary congestion, peripheral oedema, anaemia, or signs of pruritus.
Investigations
Bedside
- Check blood pressure in all patients
- Urinalysis for proteinuria, microscopic haematuria, and to rule out active urine infection. Glucosuria may also been seen in poorly controlled diabetes (or with SGLT2 inhibitor use).
- A urine sample should then be sent for urine albumin-creatinine ratio (uACR)
Serology
- Urea and electrolytes including eGFR Any acute decline in eGFR should be repeated within 14 days to exclude an acute kidney injury (AKI), which then requires urgent assessment.
- Full blood count and iron levels – Patients with advanced CKD may develop anaemia of chronic disease and iron deficiency. Anaemia may also be seen in individuals with myeloma.
- Bone profile (including phosphate and parathyroid hormone (PTH) levels) – Patients with advanced CKD may develop elevated phosphate levels and secondary hyperparathyroidism. Hypercalcaemia may suggest underlying malignancy (especially myeloma) and can adversely impact renal function.
- Serum bicarbonate – Acidosis is common in advanced CKD.
- Auto-immune screen – In patients with suspected glomerulonephritis a soluble immunology screen should be sent. Typically, this will include ANA, ANCA, anti-GBM antibodies, DsDNA and complement.
- Immunoglobulins and serum free light chains – These may be elevated in myeloma.
- Anti-PLA2R antibodies – Present in the majority of cases of primary membranous nephropathy, which usually presents with nephrotic syndrome.
- Virology – screening for HIV, Hepatitis B and Hepatitis C should be undertaken as these conditions can be associated with renal disease.
Imaging
A urinary tract ultrasound is usually the best modality to look for structural kidney abnormalities or urinary tract obstruction, and may show radiological signs of CKD. It is also helpful when planning for a kidney biopsy. A CT scan may be more appropriate if there is suspicion of renal stones or malignancy.
Kidney biopsy
Percutaneous kidney biopsy remains the gold standard investigation for diagnosis of intrinsic renal disease. Indications include unexplained renal impairment (especially when progressive) to identify potentially treatable causes, and in patients with suspected glomerular disease or interstitial nephritis. In these cases a biopsy is important to confirm the diagnosis and to inform clinical decision making, such as the need for immunosuppression. Biopsies can also play an important role in prognostication by quantifying the extent and chronicity of tissue damage, when risks associated with some treatments may outweigh potential benefits.
As with all invasive procedures there are risks associated with kidney biopsy, most notably the risk of bleeding which can be life-threatening in rare cases. For this reason, the decision to undertake a kidney biopsy should be carefully considered and patients counselled appropriately, especially for those at highest risk. High risk groups include individuals with a single kidney, uncontrolled hypertension, small kidneys, blood clotting disorders, obesity, and frailty or confusion that impact on ability to follow instructions during the procedure.