Presentation on theme: "Assessment of a Patient with Renal Disease Dr Andrew Stein Consultant in Renal and General Medicine, UHCW."— Presentation transcript:
Assessment of a Patient with Renal Disease Dr Andrew Stein Consultant in Renal and General Medicine, UHCW
Aims Anatomy Function Definitions – eGFR, CKD, Creatinine History Examination Investigation Likely Cases
Theme of Lecture: Basic Renal Principles Assessment of a renal patient is not that complicated, need to be methodical.. History, esp DRUGS Examination, esp fluid state Careful analysis of data Exclusion of non-renal causes of symptoms Re-assess patients daily (fluid state) Some technical knowledge of dialysis/Tx etc
Normal (Basics) Normal bladder size – mls Normal urine output – 2L/day (urinate 8x in day, 1x/night ≈ 200 mls) – Oliguria < 400 ml/day – Oligo-anuria < 200ml/day – Anuria = zero ml/day
Kidney Size 12 (10-14) x 6 x 3 cm, 150g, retroperitoneal How does that affect palpation?
Kidney Palpation Normal kidneys are not usually palpable However, in some slim women, lower pole of the right kidney can occasionally be felt during deep inspiration Large kidneys or masses can sometimes be felt
Functions of Kidney Execretory (3) 1.Excretion of waste products 2.Regulation of fluid state and electrolytes 3.Acid-base balance Metabolic/endocrine (4) 1.Erythropoitein 2.Renin 3.Prostagladins 4.Activation of vitamin D Consequences?
How Hard do 2 Kidneys Work? 25% cardiac output GFR 120 mls/min = ~ 170 L /day Ie blood volume passes through kidneys 35x/day
What is GFR? Why Measure it? Glomerular filtration rate (GFR) is the rate (volume per unit of time) at which ultrafiltrate is formed by the glomerulus. Approximately 120 mL are formed per minute We use GFR to estimate renal function GFR α 1/creatinine, ie mathematically linked Whats wrong with creatinine? – A normal creatinine concentration can occur even when the GFR has dropped by 50% – So creatinine is a fairly insensitive indicator of early renal impairement Creatinine clearance and the assessment of renal function Nankivell, BJ. Aust Prescr 2001; 24: 15-7
CKD: GFR α 1/creatinine Creatinine GFR 120 mls/min Creat <120 mcmol/L Why GFR? Creatinine is rel specific but not very sensitive Creat GFR/% Do Prepare Think
Factors Affecting Serum Creatinine Age Sex Race Muscle mass, useage Diet Drugs (eg?) Creat 200 GFR 60 mls/min Creat 200 GFR 15 mls/min Needs dialysis
Other Problems with Creatinine Creatinine is an imperfect filtration marker, because it is secreted by the tubular cells into the tubular lumen, especially if renal function is impaired The amount excreted exceeds the amount filtered by 10-20% Fortunately this is balanced by a similar error in the chemical assay used which overestimates serum creatinine So. Above 40 mls/min, the serum creatinine is accurate and good reflection of GFR. Under this level, it tends to overestimate GFR Note: some drugs (such as cimetidine or trimethoprim) have the effect of reducing tubular secretion of creatinine. This increases the serum creatinine. These drugs are not often used now
Can Urea Be Used? Measuring the blood urea concentration has limitations because, as well as renal impairment, it is increased by: – Increased protein metabolism (raised in catabolic states, and high protein diet) – Dehydration – Heart failure – RVD – Steroids And, conversely, patients with renal impairment can have relatively normal blood urea concentrations if they are grossly malnourished and not eating
What About Tubular Function? Although glomeruli control the GFR, damage to the tubulointerstitium is also an important predictor of GFR and progression towards renal failure Renal tubules make up 95% of the renal mass, do the bulk of the metabolic work and modify the ultrafiltrate into urine They control a number of kidney functions including acid-base balance, sodium excretion, urine concentration or dilution, water balance, potassium excretion and small molecule metabolism (such as insulin clearance) Measurement of tubular function is impractical for daily clinical use, so we usually use the GFR to assess renal function
Definitions of Normal Renal Function, Renal Impairment and Failure in AKI/CKD (Creatinine + GFR) AKI/AKI-CKD Creat >120 mcmol/L (normal range ) RIFLE (research mainly) CKD Creat >120 mcmol/L (normal range ) GFR < 120 mls/min (not used in AKI) Renal impairment = CKD <60 mls/min (CKD3a) Renal failure = <15 mls/min (CKD4) Simple Definition of Renal Impairment = Creat > 120 mcmol/L (AKI, CKD, or AKI-CKD)
CKD, eGFR, Creatinine and Symptoms CKD1 – creat N (<120) CKD2 – creat N (<120) CKD3a – creat N-150 CKD3b – creat CKD4 – creat >200 CKD5 – creat >400 When do symptoms start? Who to refer?
Another Way of Describing Renal Impairment
Classification of AKI: RIFLE RIFLE (Bellomo, 2004)Creatinine R isk1.5-2x baseline I injury2-3x F ailure>3x L oss(>4 wks) E SRD(>3 mths) Later: AKIN, KDIGO, NICE (2013)
Anuria V rare Only 3 causes – Obstruction – Vascular catastrophe – Severe acute glomerulonephritis
Macroscopic Haematuria Recurrent visible haematuria Age > 40 years, presume neoplasia Smoking UTI/stones or other urological disorders Occupational exposure to chemicals or dyes Pelvic irradiation Excessive analgesic use Cyclophosphamide
Examination General Limited cardiorespiratory GI+
General Examination “Observation is 90% of Medicine” Prof Dan Hoyte Walk into the room (DM?) Face (eg SCCs (Tx-related), SLE) Hands (radial/brachial fistula) Skin (excoriation) Uraemic frost = deposition of white/tan urea crystals on the skin after sweat evaporation (v rare) Pulse (sign of LVF)
Cardiorespiratory = Limited cardiorespiratory BP BP BP JVP JVP JVP Auscultation (pericardial rub) Pulmonary oedema (± pleural rub) Sacral oedema Leg oedema
GI+ Observation (state the obvious, eg.. ) Light palpation Deep palpation Liver Spleen Kidneys + Bladder Bruits (epigastric, femoral)
Urine - MSU <5 WC <25 RC No casts (esp red cell) No growth “Mixed growth”?.. which UTIs to investigate?
Dipstick – Blood, WC, Glucose Haematuria 2+ (ie microscopic) = ? – 80% sensitive, 65-99% specific – Need?.. Leucocytes 1+ ≠ UTI (need?..) Nitrites - produced when bacteria reduce urinary nitrates derived from amino acid metabolism Glucose - usually appears in urine when serum glucose increases to > 10 mmol/L) and renal function is normal Useful screening test, not diagnostic
Microscopic Haematuria – Who to Investigate If associated with: Stage 4 or 5 CKD Worsening CKD Significant proteinuria (PCR ≥ 50, ACR ≥ 30 mg/mmol (≥ 0.5 g/24h)) Uncontrolled BP ≥ 140/90 mmHg (3+ drugs) Or unexplained microhaematuria following urological assessment where no cause was found
Dipstick - Protein Detects albumin but not other proteins, such as immunoglobulin light chains (consequence?..) Like creatinine, his test is specific(ish), but not very sensitive for the detection of proteinuria Ie, it becomes positive (1+) only when protein excretion exceeds 0.5 g/L (upto 0.2g/L is normal). This is quite a lot Hence, concept of microalbuminuria developed
Dipstick – Protein (Other Problems) Semi-quantitative categories on the dipsticks should be used with caution (esp ‘proteinuria’ = albuminuria) Only a rough guide since Albumin conc varies with urine volume, ie – Dilute urine underestimates degree of proteinuria – Concentrated urine may show ‘3+ proteinuria’ Different products
Proteinuria (quantification) Eat 80g /day Heavy proteinuria is the hallmark of glomerular disease Normal = <0.2 g/L, ie <0.4g/day, if 2L urine Or PCR <15 mg/mmol (ACR <3 mg/mmol) PCR/100 ≈ g/24h ACR 3-30 mg/mmol = microalbuminuria Dipstick specific but not very sensitive (like creatinine) Dipstickg/Lg/24hPCR (ACR) 0<0.2<0.4g<15 (<3) Trace (ACR 30) (ACR 70)low modnephrotic range highnephrotic v high
Investigation – Specialised (Renal Biopsy) AKI, normal sized kidneys, no obvious cause = biopsy CKD, normal sized kidneys, no obvious cause = biopsy Proteinuria (>1g/L = 2g/24h = ‘nephrotic range’), no obvious cause Transplant dysfunction
Investigation – Specialised (Renal Angiogram) Rarely performed (now always with a review to intervention) Hypertension (RVD) with poor BP control on 4 drugs ‘Flash’ pulmonary oedema AKI in single (or single effective kidney) Fibromuscular dysplasia
Case One 47y year old Asian male Presents 2 wks SOB and SOA, O/E fluid overload DM2 2 years IHD/CCF Serum albumin 40 g/L Urinary protein 0.15 g/L 1. Other information? 2. Diagnosis?
Case Two 35y old female Investigated for BP Creat 68 mcmol/L FH grandfather died of kidney problem O/E large liver? 2 large kidneys? (both?) 1. Next investigation? 2. Diagnosis?
Case Three 23 year old female 2 weeks SOA O/E SOA Serum albumin 25 g/L Urinary protein 4.3 g/L Creat 87 mcmol/L 1. Renal syndrome? 2. Diagnosis?
Case Four 67 year old Asian male PMH DM2 (20y), TURP C/O 6 mths SOB, O/E fluid overload, R fem bruit Creat 465 mcmol/L (198 mcmol/L, 2012) Urinary protein 0.1 g/L 1. Next investigation? 2. Diagnosis?
Case Five 87y old male C/O tiredness ESKF (2009) On CAPD (4 x 2L bags a day) Creat 877 mcmol/L and stable 1. Other information? 2. Diagnosis?
Summary Assessment of a Renal Patient is not that complicated, need to be methodical.. History, esp DRUGS Examination, esp fluid state Careful analysis of data Exclusion of non-renal causes of symptoms Re-assess patients daily (fluid state) Some technical knowledge of dialysis/Tx etc