Clinical Assessment of Patients with Urinary Tract Diseasex

Clinical Assessment of Patients with Urinary Tract Disease Pathology  Impairment of selective glomerular filtration o ↓GFR o Leakage of blood components into urine • Loss if tubular functions o Loss of concentrating ability  nocturia o Loss of acid secretion  acidosis/alkaluria o Loss of filtered energy compounds (glucosuria, aminoacidura) • Impairment of endocrine function Impairment of regulatory role o Fluid retention o Waste produce retention • Symptoms of Urinary Tract Disease • • • • Frothy urine (proteinuria) Haematuria Nocturia Oedema: proteinuria  hypoalbuminaemia  ↓ osmotic pressure in blood  Breathlessness: o Pulmonary oedema o Severe haematuria  anaemia o ↓ EPO production  ↓ RBC  anaemia  Headache: o Endocrine dysregulation o Salt or fluid retention  hypertension • • • • • Nausea/confusion/itchiness: accumulation of toxins in blood Loin pain: kidney pain/inflammation Renal colic: ureteric obstruction Irritable urinary symptoms (cystitis) Obstructive symptoms Half-and-Half Nails/Lindsay Nails • • • • Distally pink or brown Proximally pale Absent lunulas Specific but insensitive sign of CKD Renal Investigations • • • • • Serum electrolytes Urea and creatinine Albumin, Ca2+ and PO43Urine microscopy for RBC morphology and casts Tests to determine urinary protein Serum Solutes: • • ↑K found in advanced kidney disease ↓HCO3- in advanced kidney disease o Due to accumulated acid o HCO3- + H+  H2CO3  H20 + CO2 • • • • ↑Urea: by-product of protein metabolism, accumulates in renal diseases ↑PO43- in advanced kidney disease ↓Ca in advanced kidney disease ↑Creatinine in kidney disease, used to measure GFR Creatinine • • Generated in skeletal muscle Freely filtered in glomerulus, minimally tubularly secreted  Serum creatinine depends on: o GFR o Muscle mass (very minor determinant) • GFR is calculated in two ways o 24hr clearance of creatinine o GFR equation Estimated GFR (eGFR) 1. Cockroft-Gault Equation 140 − age × weight (kg) GFR = (× 0.815 if female) 0.815 × serum creatinine (μmol/L) • • Not corrected for body surface area Recommended equation for when doses need to be changed to do altered renal function • Overestimates renal function at low GFR 2. MDRD Equation • • • Needs only age and gender to estimate eGFR corrected to BSA not validated for many ethnic groups 3. CKD-EPI Equation • • Improved version of the MDRD equation Most commonly used • • • • Therefore, eGFR results to a percentage of max renal function Inaccurate at extremes of age Inaccurate if there is acute kidney injury Inaccurate if there is abnormal muscle bulk o Creatinine is produced in muscles and excreted by the kidneys o High creatinine: ↑muscle bulk or low renal function o Low creatinine: caused by degenerative muscle disorders and malnutrition Urine Microscopy • Exams warn urine under phase contrast microscope  Provides information on: o Cellular components (RBC, WBC, tubular cells) o Urinary casts o Urinary crystals Proteinuria • Normal urine has ~200mg of non-albumin protein per 24hrs o Small MW proteins o Proteins arising from tubular brush border   • Tamm-Horsfall protein Cause hyaline casts Protein in urine can be measured by o Timed collection   Collect urine for 8 or 24 hours Measure albumin or protein content  Check creatinine excretion to determine if collection is complete o Correcting measured concentration of protein for relative concentration curve  If 2g of albumin is excreted in 24hrs, the concentration of albumin will be twice as high if volume of urine is halved  Spot urine sample: o Early morning urine recommended o Measure albumin concentration (mg/L) o Measure creatinine concentration (mmol/L) (this is inversely related to urine concentration o Expressed as albumin to creatinine ratio (mg/mmol)