Laboratory Urinalysis

Laboratory urine analysis

Microscopy

  • Uncentrifuged specimen
  • Examine for red cells, white sells and epithelial cells
  • Pyuria (>10 x 106 /L) indicative of the presence of inflammation
    • Pyuria is usually, but not always associated with significant bacteruria
    • White cells can be associated with non-infectious conditions such as calculus, renal disease, trauma and neoplasia

Casts

  • Plugs of High MW mucoprotein form in the renal tubules and collecting ducts by agglutination of protein cells or cellular debris and flushed loose by urine flow
  • Hyaline
    • Normal if present in small amounts
    • Inflammation, trauma to glomerular capillary, renal parenchymal disease
    • Epithelial
      • Eclampsia, amyloidosis, heavy metal poisons
      • Renal tubular damage and nephrosis
      • Granular
        • Coarse or fine
        • Lead poisoning, ARF, CRF, PN
      • Fatty/waxy
        • Nephrotic, diabetes, CRF
      • RCC
        • GN, SLE, SBE, renal infarction
        • Malignant HT, collagen disease, sickle cell
      • WCC
        • Acute PN and GN
        • Lupus nephritis
      • Drugs
        • Contrast, amphotericin, isoniazid, frusemide, penicillin, sulphonamides, gentamicin, Bactrim

Culture

  • Urine in the bladder is normally sterile
  • In process of specimen collection contamination from urethra and periurethral areas is common
  • Count significance (Significant bacteruria)
  • Must take age, sex, clinical history into account
  • Generally accepted that >108 bacteria per litre is indicative of significant bacteruria
  • PPV >98%
  • NPV < 65%
  • 33% of acutely symptomatic females have bacterial counts below this (significant bacteruria taken as 105 in these people)

Sensitivity and specificity of microbiology tests

CCC Differential Diagnosis Series

NEURO

Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision

RESP

Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement

CVS

Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction

GIT

Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage

GUT

Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency, 

MSK

Arthritis, Shoulder pain, Wasting of the small muscles of the hand

DERM

Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans

ENDO

Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss

HAEM

Splenomegaly

PAEDS

Floppy infant 

MISC

Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest

IMAGING

CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR,
ABDO: Gas on abdominal X-ray, Kidney mass,
BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly,
OTHER: Pseudofracture on X-Ray, 

LABS

LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia, 

HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia, 

ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis,

Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes
Cite this article as: Mike Cadogan, "Laboratory Urinalysis," In: LITFL - Life in the FastLane, Accessed on March 28, 2023, https://litfl.com/laboratory-urinalysis/.

Critical Care

Compendium

…more CCC

Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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