Presenting Problems in Renal Disease

Introduction

Renal diseases can present with a wide variety of symptoms, be it due to alterations in excretory, homeostatic or endocrine functions. Presenting problems include:

• Haematuria
• Pain
• Polyuria
• Oliguria/Anuria
• Proteinuria
• Changes in urine colour
• Oedema
• Uraemia

Patients may also present with features of renal-related complications, including:

• Hyperkalaemia
• Hypertension (as occurs in renal artery stenosis or fibromuscular dysplasia)
• Anaemia
• Thrombosis (as occurs in nephrotic syndrome or renal cancers)

Haematuria

Presence of red blood cells in blood. Can be microscopic or macroscopic.

Significant haematuria includes:

1. Visible haematuria
2. Non-visible, symptomatic haematuria
3. Persistent non-visible, asymptomatic haematuria

Macroscopic haematuria

Causes include:

1. Urinary tract infection (associated with urinary nitrites/leucocytes, frequency, urgency, dysuria)
2. Renal stones (associated with colicky pain)
3. Glomerulonephritis (associated with proteinuria, hypertension, low GFR)
4. Trauma e.g. exercise
5. Bleeding diathesis
6. Renal and bladder cancer
7. Polycystic kidney disease
8. Alport’s syndrome (associated with hearing loss)

Non-visible haematuria

Urological causes include:

1. Benign prostatic hypertrophy
2. Urinary tract infection
3. Renal stones
4. Bladder/Cancer
5. Glomerulonephritis
6. Polycystic kidney disease

Pain

Urinary tract infections usually produce urethral pain.

Causes of loin pain include:

1. Renal stone
2. Pyelonephritis
3. Polycystic kidney disease

Polyuria

Polyuria refers to excess urine production; this is not the same as urinary frequency, which describes the need to urinate more often. Polyuria is usually accompanied by polydipsia.

Causes

1. Diabetes mellitus
2. Diuretics
3. Heart failure
4. Electrolyte disturbance: Hypercalcaemia, hypokalaemia
5. Hyperthyroidism
6. Primary polydipsia
7. Uraemia
8. Diabetes insipidus

Investigations for polyuria

1. Glucose measurement
2. Urine dipstick
3. Urine Osmolality: low osmolality suggests diabetes insipidus, while high osmolality suggests inability to reabsorb solutes
4. Urea and electrolytes blood test
5. Calcium levels
6. Thyroid function

Poor urine output (oliguria/polyuria)

Normal urine output 0.5-1ml/kg/hr. Oliguria is defined as urine output of <0.5ml/kg/hr, while anuria refers to the absence of urine production.

Normal urine output relies on the following factors:

1. Adequate blood supply (pre-renal condition)
2. Functioning kidneys (renal condition)
3. Urine outflow from kidneys (post-renal condition)

Causes

Pre-renal causes of reduced urine output include:

1. Hypovolaemia
2. Hypotension e.g. sepsis, pancreatitis
3. Heart failure
4. Reduction in local renal perfusion e.g. renal emboli, dissecting aneurysm

Renal causes of reduced urine output include:

1. Acute tubular necrosis
2. Glomerulonephritis
3. Interstitial nephritis e.g. NSAIDs, antibiotics
4. Vascular:
   1. Vasculitis
   2. Haemolytic uraemic syndrome
   3. Thrombotic thrombocytopaenic syndrome
   4. Disseminated intravascular coagulopathy
5. Infection:
   1. Malaria
   2. Legionella
6. Multiple myeloma

Post-renal causes of reduced urine output include:

1. Benign prostatic hypertrophy
2. Blocked urinary catheter
3. Neuropathic bladder
4. Pelvic mass e.g. malignancy
5. Retroperitoneal fibrosis
6. Bladder stones
7. Trauma
8. Surgical complication

Investigations

Examining the abdomen to check for a palpable bladder and inserting a urinary catheter would help in excluding a post-renal cause. Differentiating prerenal from renal disease can be done by clinically examining the fluid status of the patient, measuring U&E and urinalysis.

1. Blood tests, including U&E: prerenal disease has a disproportionate increase of urea compared to creatinine
2. Urinalysis: in contrast to prerenal disease, renal disease typically has low urinary osmolality and high sodium excretion
3. Review fluid charts
4. Urinary catheterisation
5. Urinary ultrasound scan – checks for hydronephrosis

Proteinuria

Proteinuria refers to excretion of protein in urine. It should be considered if urinary albumin:creatinine ratio is >30mg/mM or protein:creatinine ratio is >45 mg/mL.

High excretion of protein for 3 months or longer suggests chronic kidney disease.

Causes of proteinuria

Transient proteinuria can be caused by:

1) Vigorous physical activity

2) Fever

3) UTI

4) Orthostatic proteinuria

Persistent proteinuria (lasting >2 weeks):

1. Glomerular (increased glomerular permeability): Glomerulonephritis.
2. Tubular (due to inadequate protein reabsorption):
   1. Tubular injury e.g. acute tubular necrosis
   2. Interstitial nephritis
   3. Urinary track obstruction
3. Overflow (due to increased protein production):
   1. Light chain cast nephropathy
   2. Rhabdomyolysis
   3. Polymyositis

Symptoms associated with proteinuria

Symptoms of proteinuria include the production of ‘frothy’ urine. Additional features can include:

1. Peripheral oedema: Nephrotic syndrome
2. Haematuria:
   • Nephritic syndrome
   • Goodpasture’s syndrome
   • Polycystic kidney disease
3. Pain:
   • Polycystic kidney disease
   • Urinary tract obstruction

Investigations for proteinuria

1. Quantify proteinuria – use urinary albumin:creatinine ratio or protein:creatinine ratio
2. Glucose levels
3. Urea and electrolytes

Change in urine colour

Several conditions and drugs can produce a change in urine colour. Examples of these are summarised below.

Orange urine

1. Conjugated bilirubin.
2. Rhubarb consumption
3. Senna

Brown/black

1. Conjugated bilirubin
2. L-DOPA
3. Alkaptonuria

Red

1. Blood
2. Porphyrins
3. Beetroot consumption
4. Rifampicin, warfarin, metronidazole

Green

1. Propofol
2. Fluorescein

Oedema

Oedema can occur in renal disease when proteins are inappropriately excreted (e.g. nephrotic syndrome). This leads to a loss of plasma oncotic pressure, leading to fluid shifts from intravascular to extravascular compartments.

Uraemia

Uraemia is the presence of raised urea levels in blood.

Causes

1. Reduced renal perfusion
2. Chronic kidney disease
3. Outflow obstruction
4. ↑ Hepatic production e.g. high protein diet

Clinical features

Uraemia can present with a wide range of symptoms and signs but may also be asymptomatic. Clinical features may include:

1. Neurological: Nausea/vomiting, encephalopathy, seizures
2. Constitutional: Fatigue, anorexia
3. Dermatological: Pruritus
4. Cardiovascular: Pericarditis