Renal disease Flashcards
Some words about the kidenys
What happens when renal perfusion and glomerular filtration fall?
11-14cm length Retroperitoneal at sides of: T12-L3 Funtional unit: nephron 25% of cardiac output. PCT: reabsob most filtered solute, but elimination of K, H2O and not volatile H+ in DCT.
Reabs of water and sodium by PCT increases so that minimal fluid reaches DCT—> hency hypotensive or hypocolaemic pts cannot excrete K and H+ ions.
Pts with distal tubular damage eg caused by drugs - also cannot exrete K+H.
Role: elimination of wastes.
Regulation of volume + fluid composition
Produce erythroprotein, renin and vit D in avtive form.
What are some presenting complaints of renal disease?
Most common: benign prostatic hypertophy in men and UTIs in F.
Sx suggesting renal tract disease: frequency of micturition, dysuria, haematuria, urinary retention, and alteration of urine vol. either polurea or oligouria.
Pain: from loin to groin.
Non specific sx: pruritus- CKD
Asx and discovered by mistake on HTN, raised serum urea, proteinurea or hameturia on Stix testing.
What happens in dysuria?
Pain on micturition
1. Inflammation of urethra- urethitis or cystitis (bladder) .
Common in adult women usually lower B UTI. W/ inflm in urethra and bladder. Others: Chlamydia trachomatis or Neisseria gonorrhoea.
- Inflammation involving vagina or penis or glans in penis: Candida albicans and Gardnerella vaginalis.
What happens in polyuria and nocturia?
Poly: total UO> 3L in 24hrs.
Causes: polydypsia, solute diuresis ( hyperglycaemia with glucosuria), Diabetes insipidus amd CKD.
Nocturia: drinking before bed, or in men >50, prostatic enlargement.
Oliguria- what happens and what do we have to do?
How do we manage oliguria?
1: exclude outflow obstruction: acute retention of urine, great discomfort. Bladder is palpable as a mass. Dull to percuss.
Dx confirmed by passing catheter and releasing large vols of urine.
If already catheterised, should be flushed with sterile saline to remove any blockage.
Obstr proximal to bladder- eg ureteric- is often painless amd USS- exclude pelvicalceal dilatation.
- Asses for hypovolaemia- measure BP, pulse, JVP, urinary electrolytes. 500ml saline iv over 30mins.
- Mx of established AKI- once first two excluded.
How do we investigate for renal disease?
GFR- to define the exact level of renal fx.
Hx and exam, + stix testing + urine microscopy. To determine cause.
+ bloods.
Creatinine clearance- accurate GFR measurment over 24hrs.
Urine stic testing: detects: ketones, protein, glucose, bilirubin, urobilinogen, and blood, pH useful in renal tubular acidosis mx.
What do blood tests represent?
Serum urea + creatinine= dynamic equilibrium b/w production and elimination. Levels do not rise above normal range until GFr reducyion of 50-60%.
Serum urea raised: high protein diet, increased tissue catabolism (surgery, trauma, infx) amd GI bleed.
Creatinine: more related to age, sex and muscle mass. Once eleveated, better guide than urea, but does not follow GFR.
What happens in proteinuria?
Up to 200mg/24hrs normally.
>150mg/24hrs is abnormal.
>2g/day- glomerular disease.
>3.5g nephrotic syndrome.
Phosphaturia: Fanconis syndrome.
Bemce Jones proteins( immunoglobulin light chanis) not detected on stix- immunoelectrophoresis.
Microalbuminaemia- >30mg/24grs. Early indicator of diabetic glomerular disease- preictor of nephropathy in diabetics.
Detected by 24-hour urine sample or comparisom of albumin comc to creatine comcentration in a random urine sample.
Generally an albumin:creatinine ratio of 2.5:20 corrsponds to albuminuria of 30-300mg per 24hrs.
Haematuria
Can be macroscopic and microscopic- so a postive stix stix text must always be followed by carefull microscopy for red cell casts + exclude hamoglobimuria and myoglobinuria (uncommon).
Signs of glomerular bleed: red cells casts, proteinuria + renal impairment.
P⬇️ absence of these:
Urine cytology, renal USS, excretion urograpgy and cystoscopy required to identify site of bleed.
IgA nephropathy: often the ones with isolated haematuria + -ve radiological and cystoscopic findings. –> referred to renal physician.
For renal biopsy consideration. (Not usually perforemed)
Macroscopic: Hx + only apparent at start of micturition + assc w/ urethral disease.
If at end: bleeding at prostatic base of bladder base.
Even discolouration theouout urine: bleeding from bladder and above.
What happens in glycosuria?
DM must be excluded in any +ve stic test.
What happens in urine microscopy?
Perfomed on all suspected of have a +ve Stix test.
White cells. >10 - inflammatory rctn, usually UTI. Sterile pyuria - pus w/o bacterial infx occurs in partially treated UTIs, urinary tract TB, caliculi, bladder tumour,mpapillary necrosis and tubulointerstitial nephritis.
Red cells: abnormal and must be investigated.
Casts
Bacteria: >10stin 5i. Or 10-3 of pathogenic organism per mL of urine in a symptomatic pt.
In women, dx also made with 10-2 per mL in pyuria.
Are casts a normal finding in microscopy?
Yes- mucoprotein precipitated in renal rubules -> hyaline casts.
But
Red cell casts- oathognomonic glomerulonephritis. Neohritic syndrome.
White cell casts- acute pyelonephritis.
Granular casts- disintegration of cellular debris- renal disease.
When is a plain Xray needed?
Identify renal calcification or radiodense calculi in:
Kidney
Renal pelvis
Line of ureter or bladder
When is IV urography used? IVU
Aka IVP- pyelography- relapced by renal CT or USS.
injection of iodine contrast- calceal dilatation, filling defects- stones, tumour.
Allergic rcts,
Bronchospasm,
Urticaria,
Rare- hypotemsion.
