The Renal System:History-Taking & Urine Analysis

Clinical Skills

2013

Anatomy Gross structure – 2 adult kidneys approximately

150g each, lying retroperitoneally in the abdominal cavity on either side of the vertebral column at level of T12 – L3

Renal vasculature – renal artery and vein Urine drains via pelvis of kidney into the

ureters, which cross over the pelvic brim to drain into the bladder (NB pelvi-ureteric and vesico-ureteric junctions – note VUR associated with a congenital defect)

Bladder, trigone, urethra, sphincter

Functions of the Kidney

Controls volume, osmolarity and acid-base balance of plasma and EC fluid, as well as the level of electrolytes

Recovers small molecules filtered by the nephron, such as amino acids and sugars

Excretes nitrogenous waste from protein metabolism, mainly urea, uric acid and creatinine

Functions of the Kidney (cont)

Excretes toxic metabolites and excess electrolytes and water

Maintains red cell production by the secretion of erythropoietin

Maintains calcium balance by production of the active form of Vitamin D

Controls blood pressure

SPECTRUM OF DISEASE

Congenital abnormalities Interstitial nephritis Glomerulonephritis Cystic kidney disease Renal vascular disease Nephrotic syndrome Renal failure Infections of the urinary tract Obstruction of the urinary tract Urinary tract calculi and nephrocalcinosis Malignancy of the urinary tract eg CA bladder Incontinence

History-Taking

Gathering of information Patient narrative Biomedical perspective Psychosocial perspective Context

Cardinal symptoms of diseases of the urinary tract – presenting complaint/s

Abnormalities of micturition Pain presentations Alteration in the appearance of urine Alteration in the amount of urine General symptoms of abnormal renal function

ABNORMALITIES OF MICTURITION

Dysuria Frequency and nocturia Urgency Hesitancy, decreased stream and

dribbling Retention Incontinence

Dysuria

Dysuria = pain / discomfort during micturition

Often referred to as burning on micturition

Associated with cystitis or urethritis

Frequency and nocturia

Frequency = the need to pass small amounts of urine frequently

Due to bladder irritation – may be caused by infection, stone, tumour

Nocturia = waking up to pass urine at night (pregnancy - pressure, diabetes – associated with polyuria)

Urgency

Urgency = a sudden compelling need to urinate

Caused by local irritation or inflammation

Hesitancy, decreased stream and dribbling

Hesitancy = delay /difficulty in initiating micturition

Poor stream Dribbling = terminal dribbling after

passage of urine Associated with urinary obstruction –

often associated with prostatism or bladder outflow obstruction in elderly men

Retention

Retention of urine - due to obstructive lesions such as stricture, benign prostatic hypertrophy or BPH, tumour

May be heralded by the phase of hesitancy

Incontinence Incontinence is the inability to hold urine in the bladder

voluntarily Spinal cord lesions are associated with retention and

overflow neurogenic incontinence Prostatic enlargement is associated with overflow

incontinence – dribbling incontinence after incomplete urination

Stress incontinence – more common in women – leakage of urine after sudden increase in intra-abdominal pressure eg due to coughing or sneezing, and associated with bladder prolapse

Urgency incontinence – associated with urgency and caused by local irritation or inflammation

PAIN PRESENTATIONS- renal, ureteric, vesical, urethral

Renal angle pain - dull ache between 12th rib and erector spinae muscle on the side of the affected kidney – pyelonephritis. (Refer renal angle tenderness)

Renal colic – due to ureteric obstruction – a severe pain – lumbar region; radiates to abdomen, groin, testes, thigh – due to stone or tumour

Ureteric colic – spasmodic, severe pain during the passage of a renal calculus; radiation path of renal colic; may be associated with vomiting, sweating.

Suprapubic pain from bladder / urethra is referred to lower abdomen, perineum and glans penis in males

ALTERATION IN URINE APPEARANCE

Change in colour eg

Orange -Rifampicin

Red -blood

Black - malaria

ALTERATION IN AMOUNT OF URINE

Polyuria Oliguria Anuria

Polyuria

Passage of > 3 litres of urine per day Physiological – ingestion of large quantities of

fluid or substances containing diuretics Pathological - Chronic renal failure or CRF – associated

polydipsia - Diabetes mellitus – associated polydipsia - Diabetes insipidus – neurohypophyseal or

nephrogenic - Oedematous states – after administration of

diuretics

Oliguria

Passage of < 500ml of urine per day Physiological - under conditions of

water deprivation Prerenal conditions – shock,

dehydration, haemorrhage Renal – Acute renal failure or ARF

Anuria

Passage of <50 mls of urine in a day Some causes:

Renal infarct

Dissecting aneurysm

Complete ureteric obstruction

Notes re Renal Failure Occurs when glomerular filtration is

compromised May also be the consequence of abnormal

tubular function Prerenal – due to decreased renal perfusion eg

hypotension due to massive blood loss or cardiac failure

Renal – due to disease of nephron, glomeruli, microvasculature (cf DM) or tubules (cf acute tubular necrosis)

Postrenal – due to obstruction to outflow or recurrent ascending infections

Renal Failure (cont)

Acute renal failure – sudden deterioration of renal function, usually reversible

Chronic renal failure – longstanding and progressive impairment of renal excretory function – may be insidious in onset

Clinical consequences of renal failure Hypertension – renin secreted in response to impaired

perfusion – activates ACE to convert angiotensin I – II – vasoconstriction – aldosterone secretion – sodium and water retention (renin- angiotensin-aldosterone system)

Anaemia – erythropoietin deficiency Hypoproteinaemia due to protein loss – wasting and

malnutrition Renal osteodystrophy from failure of hydroxylation of

Vitamin D to active form (2º hyperparathyroidism) Other metabolic complications eg gout (defective

excretion of uric acid), endocrine and neurological complications

GENERAL CLINICAL FEATURES OF RENAL DISEASE Renal oedema Increased BP - see previous slides on

renal failure

GENERAL FEATURES (cont) Other symptoms and signs of renal failure:

AnaemiaPurpura plus GIT bleedingUrogenital symptoms – polyuria, polydipsia etcCardiovascular symptomsGIT symptoms – anorexia, nausea & vomiting, loss of weight, ammonia smell on the breathSkeletal abnormalities – metabolic bone disease

Growth retardation in children and other endocrine problems including gynaecomastia in men

Neurological symptoms such as depressed cerebral function and convulsions in severe uraemia

HISTORY-TAKING (cont)

History of presenting complaint to be in detail – chronology is important, especially in chronic conditions

Don’t forget the systems enquiry – to cover specific relevant aspects

HISTORY-TAKING - Context

Past HistoryPreceding throat or skin infection - StrepRecurrent UTIRenal stoneHT, DM, hyperuricaemia (gout)Childhood enuresis > 3 years of age (may be associated with vesico-ureteric reflux and renal scarring)HIV status, TB and Hepatitis B, CPast surgery or biopsy

HISTORY-TAKING - Context

Medications(Remember to ask about OTC drugs and herbal medications as well)SteroidsImmunosuppressantsAntibioticsAnti-hypertensives(know which drugs to avoid eg tetracyclines, NSAIDs)

Diet – protein, fluid, salt restriction

HISTORY-TAKING - Context

Family History

DM, hypertension

Inherited forms of renal disease eg adult polycystic kidney disease - inherited as an autosomal dominant; Alport’s Syndrome - inherited as an X-linked recessive

HISTORY-TAKING - Context

Social History

Employment – occupational exposures eg heavy metals such as Cadmium

Home circumstances, family support

Impact of chronic illness, dialysis

Smoking and alcohol use

Urine Volume & Composition

In health, the kidneys form approx 1500-2000mls of urine/24hrs

Urine is normally pale yellow in colour (becomes paler with decrease in osmolarity when large volumes of water are ingested, and vice versa)

pH is about 6 – slightly acidic

Urine composition vs that of plasma Much higher levels of nitrogenous waste

products such as urea and ammonia Much lower concentrations of glucose,

protein and amino acids Solutes such as salts eg NaCl, KCl and

NaHCO3, and urea are excreted at a fairly constant rate, independent of the volume of urine

Plasma has a constant osmolarity whereas that of urine varies widely

URINE EXAMINATION Inspection

- colour and appearance (? foamy)

- deposits - cloudiness of the urine may be due to the presence of bacteria or crystals (phosphates - white, urates – pink)

Specific gravity (1.005 – 1.035 Naish) Note SG of water is 1.000 and of plasma 1.010

- Decreased SG - CRF

- Increased SG - DM

URINE EXAMINATION

Reaction

- usually acidic Smell

- mild smell of ammonia is normal

- smell of antibiotics, foodstuffs

- fishy odour associated with UTI Quantity

- (N) in 24hrs = 1500 - 2000ml

Chemical Analysis•Chemical reagent strips eg Combur-9 “Dipstix”•Strip is dipped in urine; colour changes are measured after a set period and compared with a colour chart•Analysis of pH, protein, glucose, ketones, nitrite, bilirubin, urobilinogen, blood and leucocytes•To be demonstrated in Skills Lab

Protein:Dipstix measurement is semi-quantitative + - ++++ Causes of proteinuria– renal disease eg diabetic nephropathy, fever, post-operative, CCF, orthostatic proteinuriaGlucose: Causes of glycosuria – usually diabetes mellitus, also renal glycosuria (Note false positive and negative results eg large doses Vit C)Ketones: Causes of ketonuria – diabetic keto-acidosis and starvation

Nitrite: – positive due to infection with bacteria that produce nitrite – correlates well with UTI (inaccurate results with Vitamin C ingestion)Pus (WBCs):Causes of pyuria (pus in the urine) Urinary tract infection UTI Sterile pyuria in renal tuberculosisBlood: – positive dipstix is abnormal (Causes of haematuria, haemoglobinuria, etc – see next slide)

Causes of haematuria – examples: Renal causes – glomerulonephritis, renal carcinoma, analgesic nephropathy, bleeding disorders, trauma Urinary tract – cystitis, calculi, tumourCauses of haemoglobinuria – examples: Intravascular haemolysis eg haemolytic anaemia, march haemoglobinuriaCauses of myoglobinuria – examples: Convulsions, viral myositis, toxins such as snake venom (due to muscle destruction)

Microscopy – ref TalleyMSU - NB Method of collection – need a clean uncontaminated specimen using a sterile urine jar• Microscopic examination of a centrifuged specimenLook for:• RBCs – circular, without a nucleus – uniform if from the urinary tract, dysmorphic if from the glomeruli , usually 0, < 5 per lpf in very concentrated urine• WBCs – lobulated nuclei < 6 per hpf – up to 10 may be present in very concentrated urine• Epithelial cells • Bacteria – infection or contamination• Casts - cylindrical moulds formed in the lumen of renal tubules or collecting ducts - size determined by the dimension - they indicate damage to the glomerular basement membrane or tubule

Types of casts

Hyaline casts - < 1 per lpf, consist of Tamm-Horsfall mucoprotein secreted by renal tubules, may contain 1-2 RBCs or WBCsGranular casts – consist of hyaline material containing fragments of serum proteinsRed cell casts – always abnormal – indicate primary glomerular disease, contain 10-50 RBCs – post-Streptococcal GN, SBE etcWhite cell casts – WBCs adhere to inside of cast – usually indicate bacterial pyelonephritisFatty casts – these suggest nephrotic syndrome

Culture and Sensitivity

To identify organism in infectionsTo assess sensitivity to anti-microbials

References

• Past protocols• Medical Science, Jeannette Naish et al Chapter 14 The Renal System• Clinical Examination, Talley and o’ConnorChapter 6 The Genitourinary System• Principles and Practice of Medicine, Davidson