Nephrology Flashcards
Components of eGFR
Creatinine
Age, Gender, Race (Weight)
Creatinine
What
Cr vs eGFR
Chemical waste product from muscle metabolism (Muscley people have lots)
Therefore Cr clearance is > GFR - Because secreted as well as filtered!
Therefore inhibitors of secretion will make Cr rise and function look worse e.g. trimethoprim
Volume control
Aldosterone
Angiotensin II
ANP
Aldosterone (adrenal) -> decreased excretion
Angiotensin II -> decreased excretion
ANP - released by heart in response to high pressure -> increases excretion
Renal blood pressure control
Via volume control and vasoconstriction
Decreased BP at afferent arteriole -> juxtaglomerular apparatus -> renin
Prostaglandin - Preferentially dilates afferent arteriole
Angiotensin II - Preferentially constricts efferent arteriole (maintain GFR)
Antihypertensives -> ACEI (e.g. ramipril) and ARB (e.g. losartan)
ACE inhibitors
Indications
Dose
Side effects (4)
HTN, heart failure, post MI
Ramipril - start on 1.25/2.5mg PO OD at night
May impair renal function: decrease GFR (avoid NSAIDs), hyperkalaemia (avoid K+ spare diuretics)
Postural hypotension
Bradykinin mediated dry cough
Fatigue
Angiotensin receptor blockers Mechanism Indications Dose Side effects (3)
Modulation of RAAS, similar to ACEI but no dry cough
HTN, heart failure, diabetic nephropathy
Losartan - usually 50mg PO OD, elderly =- 25mg PO OD
Renal impairment
Postural hypotension
Hyperkalaemia
Location of Sodium reabsorption
PCT (70%)
Potassium control
Potassium freely filtered at proximal tubule and loop of henle
Distal secretion determines renal excretion (Na, aldosterone driven)
Hypokalaemia meds
Hyperkalaemia meds
Loop diuretics, thiazide diuretics
Spironolactone, amiloride, ACEI, ARB
Hormones functions the kindey, function & physiology
Erythropoietin stimulates RBC production
Renal cortex acts as an O2 sensor; blood flow and oxygen requirement matched.
1-alpha hydroxylation of vitamin D
@proximal tubule calcitriol increases Ca and PO4 absorption from gut and suppresses PTH
*This process is inhibited by FGF-23 which is increased in CKD
Effects of angiotensin II (5)
Increase sympathetic activity Increase aldosterone secretion Increase ADH secretion Tubular Na Cl and H2O re absorption. K excretion (aided by aldosterone) Arteriole constriction.
Mechanism of
Spirolactone
Furosemide
Thiazides
Effect of BP/Na/K
Competitive binding of aldosterone receptor
Blocks Na/Cl/K pump in ascending limp of henle
Blocks Na/Cl pump in DCT
All cause hypotension/natremia/kalaemia (besides Spiro)
Fanconi syndrome
Generalised dysfunction of renal proximal tubule -> urinary loss of bicarb, glucose, aa, phosphate, peptides, organic acids. Leads to salt wasting and volume depletion
Types of renal tubular acidosis and findings (4)
Type 1: classic distal RTA
AD or AR mutations of proton pump. Inability to excrete H+ in distal tubules.
Min urine pH > 5.5, stones, serum potassium low-normal, plasma bicarb < 10
Type 2: inherited isolated proximal
Mutation of sodium bicarbonate cotransporter that transfers bicarb back to peritubular capillary. Inability to reabsorb bicarbonate
Min urine pH < 5.5, serum potassium low-normal, plasma bicarb < 12-20
Type 4: hyperkalaemic distal
Hyperkalaemia inhibits production of ammonia and decreases urine buffering capacity
Min urine pH < 5.5, serum potassium high, plasma bicarb > 17
Fanconi’s syndrome: Myeloma proteins and various drugs cause proximal tubule injury and proximal RTA, or AD inherited, bicarb <18
Presentation of RTA
Growth retardation/failure to thrive (children)
Muscle weakness (Fanconi)
Hypoglycaemia after fructose
Rickets (Fanconi and Type 2 proximal have persistent phosphate loss)
Distal RTA with deafness may be inherited (AR - H+-ATPase)
Kussmaul breathing if severe
Management of RTA
Classic distal (T1) Sodium alkali or potassium alkali (1mmol/kg) e.g. Shohl’s solution ± potassium supplementation
Proximal (T2 and Fanconi)
Sodium alkali or potassium alkali (1mmol/kg) ± potassium supplementation ± thiazide diuretic
Hyperkalaemia + mineralocorticoid deficiency
Fludrocortisone + dietary restriction of potassium
Complications of RTA (5)
Volume depletion - loss of sodium etc at proximal tubule dysfunction
Nephrocalcinosis - classic distal, increased loads of filtered calcium because of release of calc phos and calc carb in bone buffering of acidosis
Osteoporosis - bone buffering of acidosis leads to demineralisation
Growth retardation - acidosis associated with muscle catabolism
Renal rickets - Fanconi, can’t reabsorb phosphate
Causes of end stage renal failure (4)
Glomerulonephritis
Pyelonephritis
Diabetes
PKD
Pyelonephritis
What
Bacteria
Risk factors (4)
Infection/inflammatory disease of renal parenchyma, calyces and pelvis that may be acute, recurrent or chronic
Gram -ve: E. coli (60%), proteus (15%), klebsiella (15%)
@Diabetes = klebsiella or candida
@HIV, malignancy, transplant = candida
Age - Infants and older
Anatomical abnormality - VUR, PKD, horseshoe, double ureter
Foreign body - Stone, catheter
Impaired renal function
Immunocompromised
Obstruction - BPH, stone, foreign body, bladder neck obstruction, posterior ureteral valve, neurogenic bladder
Pregnant
Pyelonephritis presentation
Tirad
Extras
Loin pain
Fever - may not be the case if patient is on steroids or anti-inflammatory
Renal tenderness/costovertebral angle
+ nausea/vomiting, DUF (associated with cystitis or urethritis), rigors
Pyelonephritis Ix (6)
URINE MC&S
-Urine dip: blood, protein, nitrites, leukocyte esterase
-Urinalysis
-Gram stain: G -ve rods (e.coli, klebsiella, proteus)
-Urine culture
FBC: leukocytosis
ESR/CRP raised
Blood culture (systemic infection SEPSIS)
IMAGING (mandatory in recurrent pyelonephritis)
*Renal USS: gross abnormality, hydronephrosis, stones, abscess
*Contrast CT: altered perfusion, structural abnormality
DMSA (renal scarring)
Pyelonephritis Mx
Mild
Severe/complicated/pregnant
Mild/moderate + uncomplicated
Ciprofloxacin (500mg PO BD 7-14D) or cefixime (400mg PO OD 14D) - 3rd gen
Severe or complicated or pregnant Admit to hospital IV ceftriaxone (3rd gen ceph) OR IV ciprofloxacin OR IV gentamicin (not to preg) IV fluids IV paracetamol (pain and fever) Catheterisation if compromised
Renal cell carcinoma
What
Types
Presentation
Renal malignancy arising from renal parenchyma/cortex
80% clear cell/adeno renal carcinoma (renal cortical parenchyma) -> due to cholesterol and glycogen
15% papillary tumor (types 1 and 2)
*Haematuria
*Flank pain
*Abdominal mass - * = classical triad <10% cases
Systemic: weight loss, anorexia, malaise
Left sided varicocele by invasion of left renal vein
Lower limb oedema