Introduction and Clinical Manifestations of Renal Disease (1)

Salwa Ibrahim, MD MRCP (UK)Professor of Nephrology

Objectives• To know basic structure and functions of the kidney

• To know main symptoms of renal disease

• To know how to assess kidney functions

Anatomy

• The kidneys are retroperitoneal organs lie on either side of the spine at level of T12-L3

• Normal kidneys are 11-14 cm in length

• Right kidney lies 1.5 cm lower than the left because of the liver

Histology

Each kidney contains one million nephrons comprising a glomerulus, PCT, Loop of Henle, distal tubule and collecting duct

Blood and nerve supply to the kidney

• The kidneys receive 25% of the cardiac output

• T10-12/L1 roots innervate the renal capsule and the ureter and pain from these structures is felt in these dermatomes

The Glomerulus

• A glomerulus is a capillary tuft that is surrounded by Bowman's capsule

• A glomerulus receives its blood supply from an afferent arteriole Unlike most other capillary beds, the glomerulus drains into an efferent arteriole

• The resistance of these arterioles results in high pressure within the glomerulus, aiding the process of ultrafiltration, where fluids are forced out of the capillaries and into Bowman's capsule

• A glomerulus and its surrounding Bowman's capsule constitute a renal corpuscle, the basic filtration unit of the kidney

• The rate at which blood is filtered through all of the glomeruli, and thus the measure of the overall renal function, is the glomerular filtration rate (GFR).

The glomerular layers

Endothelial cells

Glomerular basement membrane

Podocytes

Primary functions of the kidneys

• Excretion of waste products e.g. urea

• Maintain body water and electrolytes

• Regulation of BP through renin angiotensin system

• Endocrine function in erythropoiesis and vitamin D metabolism

The kidneys produce urine which is passes to the bladder through the ureters

As the bladder fills completely, the smooth muscle layer (detrusor) contracts under parasympathetic control to allow urine to pass through the urethra

Symptoms of renal disease

I. Kidney (upper urinary tract symptoms): Pain and swelling

II. Lower urinary tract symptoms: voiding pain (pain passing urine), frequency, urgency, hesitancy

III. Change in urine volume (polyuria, oliguria, anuria) or color (haematuria), content (proteinuria)

IV. General symptoms: oedema, fatigue, nausea, vomiting, shortness of breath

Kidney (Upper urinary tract) symptoms

Pain A. Renal colic

• A severe sudden sustained loin pain • It often radiates to the groin

• It is caused by sudden obstruction in the urinary tract usually by a calculus or a blood clot

• It is often associated with nausea and vomiting

B.Dull ache in the loins

• Usually due to stretch of the capsule of the kidney e.g. in glomerulonephritis, polycystic kidney and hydronephrosis

• Lion pain with fever, rigors, pain on voiding suggest infection of the kidneys (acute pyelonephritis)

• Many patients with chronic obstruction are however pain-free

Lower urinary tract symptoms

Dysuria

• Pain or discomfort felt during or immediately after passing urine

• It is often described as a burning sensation felt at the urethral meatus , or the suprapubic region

• The most common cause is infection and /or inflammation of the

bladder[cystitis]and frequency(desire to pass urine more often) is usually present

Voiding symptoms

Voiding symptoms

• During storage phase

• During voiding phase

• After micturition

• Incontinence

Storage symptoms

Urgency

• A sudden strong need to pass urine and may cause incontinence if there is no opportunity to urinate. Is due to overactivity of detrusor muscle or abnormal stretch receptor activity from the bladder

Frequency

• Means frequent micturition of relatively small amounts of urine

Causes

• Cystitis, urthritis or stone bladder causing irritation of the bladder wall

• Contracted bladder as occurs in Bilharziasis; the diminished capacity of the bladder leads to frequent micturition

• Chronic retention of urine e.g. by enlarged prostate small amount of urine overflow from the bladder at frequent intervals

• Cancer bladder

• Psychogenic factors as anxiety.

Voiding phase symptoms

Hesitancy: delay or difficulty in initiating urine flow

• In men over 40, it is commonly due to bladder outlet obstruction by prostate enlargement

• In women, it suggests urethral obstruction due to stenosis or uterine prolapse

Poor flow: reduction in urinary stream

After micturition symptoms

• Dribbling and incomplete emptying are caused by obstruction

• Incontinence : involuntary release of urine may occur

I. With the need to void (urge incontinence) caused by overactive detrusor

II. or with increased intra abdominal pressure (stress incontinence) due to weakness of pelvic floor following childbirth

Symptoms of bladder outlet obstruction

• Urgency

• Frequency

• Hesitancy

• Poor flow

• Dribbling

Change in urine volume

Polyuria

Means increased volume of urine as the capacity of the bladder is limited, polyuria is associated with frequency

N.B : In healthy adults urine out put will approximate to the fluid intake minus the insensible fluid losses through the skin and respiratory tract[500-800 ml/day], average 2-3 liters/day

Causes

1-Diabetes mellitus (due to osmotic effect of glucose)

2-Chronic renal failure especially with chronic tubulointertsitial fibrosis 3-Diabetes insipidus 4- Hypercalcaemia (due to impaired tubular concentrating mechanism)

5- Hypokalemia (due to impaired tubular concentrating mechanism)

6- Excessive fluid intake due to psychiatric disease.

Oliguria

Means diminished volume of urine <500 ml\day

Causes

1- Diminished intake of fluids

2- Hot weather

2- Pre-renal failure

3- Initial stage of acute renal failure

4- Terminal stage of chronic renal failure

Anuria

Means complete absence of urine formation so that no urine reaches the bladder and the patient has no desire to micturate

Causes

• lower urinary tract obstruction when bladder neck or urethral obstruction causes urinary retention

• Spinal injury through neurological damage

Change in urine colour

Haematuria

• Means passage of red blood cells in urine

• It can be

I. Macroscopic causing a reddish discoloration of the urine

II. Microscopic when excess red

cells are detected in urinary sediment

• Causes

1 -Prerenal e.g. Haemoragic diseases as purpura and over dose of anticoagulants

2-Renal e.g. Stones, tumours, glomerulonephritis, and renal T.B

3-Ureter: stone and tumours

4 -Bladder : cystitis, stone and tumours

5 -Prostate : prostatitis, prostatic hypertrophy and tumours

6 -Urethra: trauma, stricture, stone and tumours

It should be noted that

• Terminal haematuria indicates a lesion in the urethra, prostate , or bladder neck while total haematuria means the lesion is higher up

• Haematuria associative with renal colic is suggestive of stone

• Painless frank haematuria is suggestive of tumour

• Microscopic haematuria is suggestive of a parenchymatous lesion as glomerulonephritis

Differential diagnosis of haematuria (causes of reddish urine)

• Contamination of urine by menstrual blood

• Free hemoglobin due to intravascular hemolysis

• Free myoglobin in rhabdomyolysis

• Drug therapy : rifampcin

Change in urine contents

Proteinuria

Proteinuria is usually asymptomatic unless gross > 2-3 g/day

Severe proteinuria may produce frothy urine

Lowering the plasma albumin concentration, oncotic pressure

Generalized oedema and nephrotic syndrome

Nephrotic syndrome

Causes of proteinuria

1 .Renal disease

• Glomerulonephritis• Diabetes mellitus• Lupus nephritis

2. Non renal disease

• Fever• Severe exertion• Heart failure

General symptoms of chronic kidney disease

General symptoms of renal disease

• Broadly non specific

• Occur in chronic kidney disease due to retention of uremic toxins

• Nausea vomiting itching disturbed consciousness

• Fatigue and pallor secondary to anemia

• Bony aches and muscle weakness

• Shortness of breath (anemia, volume overload)

Uremic symptoms

Symptoms secondary to anemia

Symptoms secondary to bone disease

• Bone pain

• Joint pain

• Bone fracture

Symptoms secondary to volume overload

1. Lower limb swelling

2. Pleural effusion

3. Pulmonary edema

Investigations

Renal function tests

• Serum creatinine

• Blood urea

• Serum electrolytes

• Complete blood count

• Creatinine clearance

• Serum calcium and phosphorus

Urine analysis

Flat colorless hexagonal plates, which often aggregate

Red cell cast

Stix test for blood protein sugar

Cystine crystals

Flat colorless hexagonal plates which often aggregate

Microscopic examination

White cells

Phosphate crystals

Uric acid

RBCs

Radiologic assessment of UT

Plain X-ray Abdomen

Detection of calcification and radiopaque stones

Ureteric stone bilateral staghorn stones Right staghorn stone

Intravenous Pyelogram (IVP)

Hydronephrosis

Renal ultrasonography

No exposure to radiation and no dye is used

1. Assess renal dimensions2. Exclude obstruction

3. Polycystic kidney Disease

Renal biopsy

Indications

1. Nephrotic syndrome

2. Nephritic syndrome

3. Acute renal failure

4. Proteinuria, haematuria

Normal glomerulus

Membranous nephropathy

Necrotizing GN