RENAL, UROLOGY AND HAEMATOLOGY Flashcards
Why is furosemide given to patients assymetrically?
You don’t want take it too late in the day as it would cause diuresis during the night - onsets within 5 minutes but can last up to 8 hours
What does postural drop, prolonged cap refill and tachycardia all suggest?
Hypovolaemia
How do diuretics usually affect potassium levels?
They cause hypokalaemia - unless potassium sparing
What fluid do you use for fluid resuscitation after an AKI?
0.9% sodium chloride or hartmanns but be aware hartmanns has potassium in it so is contraindicated if the patient is hyperkalaemic
How do you prescribe appropriately in AKI?
DAMN
Diuretics, ACEi/ARB, metformin, NSAIDs
Why should you not give metformin in an AKI?
It’s not nephrotoxic but is 90% excreted by the kidneys and so accumulates in AKI and causes lactic acidosis
Outline why ACEi/ARB and NSAIDs are nephrotoxic especially when used together?
ACEi/ARBs block the effects of angiotensin 2 causing efferent arterioles dilation which reduces the pressure in the glomerulus
NSAIDs block the vasodilators effects of prostaglandins in the afferent arterioles so it cannot compensate for the efferent dilation and GFR reduces more
What drugs need close monitoring in AKI?
Warfarin
Aminoglycosides
Lithium
What drugs require dose reduction in AKI?
Meds that are metabolised and excreted by the kidneys should be dose adjusted for an assumed eGFR of <10
LMWH, opiates, penicillins, sulfonylureas, aciclovir and metformin
What drugs can aggravate hyperkalaemia?
Trimethoprim
Spironolactone
Amiloride
What’s the most common cause of acquired nephrogenic diabetes insipidus
When do we use creatinine clearance instead of using eGFR?
For very toxic drugs, very elderly patients and those of extreme muscle mass (if in doubt use CrCl)
Why is creatinine clearance more accurate than eGFR?
Because it includes adjustment for weight
Creatinine is used as a substrate for insulin so is nearly as accurate as an insulin measurement
Why do extremes of muscle mass affect eGFR measurements? And how do we fix this?
EGFR uses average surface area of an adult so if you have a BMI <18 or >40 then you should adjust your eGFR for increased accuracy
What can you do if there is impaired renal excretion and the half life has increased?
You can reduce the dose or extend the dosing interval
What’s the problem with gentamicin? And why do we still use it regardless?
It has a narrow therapeutic index, ototoxic, vestibulotoxic and nephrotoxic
Because its the least likely antibiotic to cause clostridium difficil diarrhoea
How is gentamicin given?
IV or IM as its not readily absorbed from the GIT
How do you calculate an appropriate dose for gentamicin?
Consider the patients lean mass (mass without excess fat) because the total body water of everyone is very similar and is hardly affected by body mass
Do use ideal body weight for the patients height
Outline why we say gentamicin follows first order kinetics?
It’s excreted unmodified buy the kidneys - drug is cleared from the blood at a rate proportional to its concentration
What are the 2 regimens used in the UK to give gentamicin?
Pharmacokinetic
Extended interval
What is extended interval dosing regimen?
Aka Hartford dosing
It’s the regimen that maximises bacterial killing whilst minimising toxicity
Give first infusion and then take a blood sample between 6 and 14 hours after. Instead of changing the dose you change the time between giving. The next dose
What is urgency urinary incontinence?
When you feel a sudden/intense need to pass urine and your unable to delay going to the toilet - there are usually only a few seconds between the need to urinate and the release of urine. It’s often associated with overactive bladder syndrome
What is stress urinary incontinence?
When urine leaks out with sudden pressure on the bladder and urethra, causing the sphincter muscles to open briefly eg. Sneezing laughing or coughing
What is mixed urinary incontinence?
Stress and urgency urinary incontinence
What is overflow urinary incontinence?
Continuous urine leakage resulting from a hypotonic bladder or bladder outlet obstruction producing urinary retention
What’s stinylates the bladder?
Hypogastric nerve (sympathetic) - NA acts on beta 3 receptor to relax bladder and acts on alpha receptor to contract internal urethral sphincter
Pelvic nerve (parasympathetic) - ACh acts on M3 receptor to contract bladder
Pudendal nerve (somatic) - ACh acts on nicotinic except or to contract external urethral sphincter
What drugs are available for overactive bladder syndrome?
Muscarinic receptor antagonists e.g. oxybutinin and tolterodine
Beta 3 adrenoreceptor agonist e.g. mirabegron
Both - relax bladder
What side effects do anticholinergic have?
BCDU
Blurred vision
Constipation
Dry mouth
Urinary retention
How is stress incontinence managed?
Pelvic floor exercises for at least 3 months
Surgery e.g. urinary sling
Vaginal oestrogens in peri-menopausal women
Duloxetine in those averse to surgery
Who is most likely to experience stress incontinence?
Women after childbirth due to damaged pelvic floor
Why do vaginal oestrogens help stress incontinence?
Because the vaginal mucosa will become atrophied after a lack of oestrogen in perimenopausal periods which can make stress incontinence worse
How do you assess the severity of BPH?
Using international prostate severity score
0-7 mildly symptomatic
8-19 moderately symptomatic
20-35 severely symptomatic
How do you manage LUTS in men?
Conservative measures e.g. pads, bladder training, urethral milking, catheterisation,
Drugs - alpha blockers for moderate to severe LUTS, anticholinergic for overactive bladder, 5-alpha reductive inhibitor to men with PSA >1.4, diuretics
Surgery
What’s the first line treatment for BPH LUTS symptoms?
Alpha blockers e.g. tamsulosin
What are the adverse effects of alpha blockers?
Othrostatic hypotension
Headache
Dizziness
Oedema
Erectile dysfunction
Rhinitis
What are the contraindications for alpha blockers?
History of postural hypotension
History of micturition syncope
Which drugs do alpha blockers reac with?
Other hypotensive agents
PDE5 inhibitors as can cause significant hypotension
What’s second line drug treatment for BPH?
5 alpha reductase inhibitors
What are the adverse side effect of 5 alpha reductase inhibitors?
Sexual dysfunction
Depression
Breast enlargement, breast tenderness impotence - affects testosterone levels
Which drugs do 5 alpha reductase inhibitors interact with?
Calcium channel blockers
What’s a contraindication of 5 alpha reductase inhibitors
Pregnanct women shouldn’t even expose themselves to them as it may cause abnormal development of the external genitalia
How do we manage prostate cancer?
Radiotherapy
Surgical prostatectomy
Anti androgens
GnRH analogues e.g. goserelin
How do GnRH analogues work for prostate cancer?
They cause an initial increase in LH and FSH but chronic administration results in the sustained suppression of pituitary gonadotropins so serum testosterone levels fall
What’s the treatment of choice for bladder cancer
Cisplatin based combination chemotherapy
How do we treat renal cell carcinomas?
Tyrosine kinase inhibitors e.g. sorafenib and sunitinib
Or mTOR inhibitor
Where do renal cell carcinomas metastasise to and why?
Lungs because they tend to grow down the renal vein which runs directly to the heart - can cause cannon ball tumours in lungs
What are the 2 ways in which iron salts can be given for iron deficient anaemia?
Oral and parenteral but only when oral therapy is unsuccessful or intolerable
What are examples of oral iron salts?
Ferrous sulphate
Ferrous fumarate
Ferrous gluconate
Why is iron from meat better than iron from plants?
Because iron from meat is heme iron which is Fe2+ and can be used directly whereas non-heme iron from plants is Fe3+ is oxygenation status need to change before being absorbed
What are the main adverse drug efefcts of iron
constipation
Black stools
Diarrhoea
Epigastric pain
GI irritation
Nausea
What drugs does iron react with and how?
Levothyroxine
Bisphosphonates
Ciprofloxacin
Tetracyclines
Calcium and zinc salts
They work by reducing gut absorption so should be taken at least 2 hours before oral iron
Why should you take iron with vitamin C?
It helps absorb it because it cotransports with iron
What’s the recommended duration of iron treatment?
Take it until Hb levels are normal and then continue for 3 months as you need to replenish bone marrow stores too
What drugs can be used for transplant immunosuppression?
Calcineurin inhibitors e,g, Ciclosporin and tacrolimus
Anti-proliferative agents e.g. azathioprine and cyclophosphamide
What’s the MOA of calcineurin inhibitors?
Inhibit calcineurin which is a key protein allowing transcription of IL-2 which inhibits T lymphocytes activation
