Chapter 9: Blood and Nutrition COPY COPY Flashcards
What are the MHRA warnings associated with epoetins?
- Risk of severe cutaneous adverse reactions including SJS.
- Overcorrection of [haemoglobin] may ^risk of death and serious CV events. CKD or chemo pts should not receive this unless symptoms of anaemia are present
- Unexplained excess mortality and ^risk of tumour progression in patients with anaemia associated with cancer who have been treated with erythropoietin
What are the main side effects of epoetins?
- Severe skin reactions and stop treatment and seek medical attention if they develop a rash (which often follow flu-like symptoms)
- Hypertensive crisis with encepathalopathy and tonic clonic seizures
- Pure red cell aplasia
What are epoetins used for?
Symptomatic anaemia in CKD or chemo patients
The daily oral dose of elemental iron for iron-deficiency anaemia should be what?
100-200mg
Are modified release iron preparations recommended in anaemias?
No - have no therapeutic advantage
In what situations would you opt for IV iron over oral iron?
When oral therapy is unsuccessful; intolerable oral iron, or not taken reliably, or if there is continuing blood loss, or in malabsorption
CKD patients on dialysis also require IV iron regularly
What are the IV forms of iron?
Iron dextran
Iron sucrose
Ferric carboxymaltose
Iron isomaltoside
Does IV iron work more quickly than oral iron?
Parenteral iron does not produce a faster haemoglobin response than oral iron provided that the oral iron is taken reliably and is absorbed adequately.
Exception: pts with severe renal failure receiving haemodialysis
IV iron does not work more quickly than oral iron except in what group of patients?
Patients with severe renal failure receiving haemodialysis
What is the MHRA advice surrounding injectable iron?
Serious hypersensitivity reactions including anaphylaxis
Pts should be monitored for such signs for 30 minutes after administration
Not recommended 1st trim. of preg. and only in 2nd and 3rd if vital
When should iron for iron deficiency anaemia be stopped?
3 months after haemoglobin is in the normal range
Are iron tablets best absorbed with or without food?
Without food
However because of the GI side effects, they can be taken with food
What are the main side effects of iron?
Constipation and diarrhoea
GI upset
Darkened stools
Most megaloblastic anaemias result from a deficiency of what?
Either vitamin B12 or folate
It is important to establish which deficiency before treatment but in an emergency can give both
What is pernicious anaemia?
An autoimmune gastritis causing malabsorption of vitamin B12
What is the choice of therapy for vitamin B12 replacement?
Hydroxocobalamin - initiated with frequent IM injections and then every 3 months
(used to be cyanocobalamin however hydroxocobalamin lasts longer in the body)
Why should undiagnosed megabloblastic anaemia not be treated with folic acid alone?
May precipitate neuropathy
If undiagnosed and needs to be given, always give vitamin B12 as well
What can be the causes of folate-deficient megaloblastic anaemia?
Poor nutrition
Pregnancy
Antiepileptic drugs
How do you treat folate-deficient megaloblastic anaemia and how long for?
Daily folic acid for 4 months
(Folic acid has few indications for long-term therapy since most causes of folate deficiency are self-limiting or will yield to a short course of treatment)
Why should folic acid never be given alone in pernicious anaemia?
Can cause compression of spinal cord
Haemochromatosis is associated with an overload of what?
Iron
Built up over several years
How do you manage haemochromatosis (result of iron overload)?
Venesection (removal of blood)
If contraindicated- long-term administration of the iron chelating compound Desferrioxamine mesilate - Vit C aids iron chelation started 1 month after desferrioxamine, taken daily, not with food.
What drug inhibits platelet formation and is used for thrombocythaemia (when too many platelets are produced in the bone marrow)?
Anagrelide
What is used in sickle cell anaemia to reduce the frequency of crises and need for blood transfusions?
Hydroxycarbamide
How do you manage severe acute hyperkalaemia?
1st = Calcium gluconate 10% slow IV injection titrated to ECG to temporarily protect against myocardial excitability
2nd = Soluble insulin IV injection 5-10u with 50 mL glucose 50% over 5-15 min, reduces serum-[K]; repeated if necessary or continuous infusion instituted
3rd = Salbutamol nebulised or slow IV injection [unlicensed] may also reduce plasma-potassium concentration
The correction of causal or compounding acidosis with Na bicarbonate infusion should be considered (important: prep of sodium bicarbonate and calcium salts should not be administered in the same line—risk of precipitation).
Drugs that exacerbate hyperkalaemia should be stopped as appropriate.
What is classed as acute severe hyperkalaemia?
> 6.5 mmol/L or presence of ECG changes
What is classed as hypokalaemia?
< 3.5 mmol/L
How do you manage hypokalaemia?
Potassium chloride
Or
Potassium bicarbonate with potassium acid tartrate.
Chronic hyponatraemia from inappropriate secretion of ADH should ideally be managed by what?
Fluid restriction
What is Hartmann’s solution?
Compound sodium lactate
How is severe hypercalcaemia managed?
Dehydration should be corrected with IV NaCl
Drugs that promote hypercalcaemia e.g. thiazides and Vitamin D should be stopped
Pharmacological management includes bisphosphonates, corticosteroids, calcitonin
When treating hypokalaemia, why shouldn’t you include glucose infusions?
That can cause a further decrease in plasma potassium concentrations
What can be given for severe metabolic acidosis?
IV sodium bicarbonate
What can be given for chronic acidotic states?
Oral sodium bicarbonate
Compared to crystalloid solution, would a larger or smaller amount of colloid solution be required for fluid resuscitation?
Smaller amount would be required of colloid
True or false:
In osteoporosis, a calcium intake which is double the recommended amount reduces the rate of bone loss.
True
What is given in severe acute hypocalcaemia/hypocalcaemic tetany?
Slow IV calcium gluconate 10%
Why should calcium gluconate IV be given slowly?
If given too rapidly, risk of arrhythmias
What is cinacalcet used for?
Hyperparathyroidism and hypercalcaemia in parathyroid carcinoma
Reduces parathyroid hormone which leads to a decrease in serum calcium concentration
Calcium carbonate is used for what two indications?
Calcium deficiency
Phosphate binding in renal failure
Aluminium hydroxide can be used for the treatment of what in renal failure?
Hyperphosphataemia
What is sevelamer used for?
Phosphate binder for CKD patients including those on dialysis
How do you manage hypercalciuria?
Find the underlying reason
Increase fluid intake and give bendroflumethiazide
MOA of thiazides is to decrease Na reabsorption and therefore decreased fluid reabsorption; this directly causes decreased levels of circulating sodium. Thiazides increase the uptake of calcium in the distal tubules, to moderately reduce urinary calcium.
What is Wilson’s disease?
Genetic disorder causing build up of copper in body tissues e.g. brain
How do you manage Wilson’s Disease?
Zinc acetate as it prevents the absorption of copper
Chelating agents are given for the first 2-3 weeks as well as zinc as zinc has a slower onset of action
Vitamin A deficiency is associated with what?
Occular defects
\_\_\_\_\_\_\_ is what vitamin? Thiamine Riboflavin Pyridoxine Retinol
B1 - Thiamine
B2 - Riboflavin
B6 - Pyridoxine
A - Retinol
Hypocalcaemia effects
convulsions, arrhythmias, numbness
<= Ca salts
Severe Vitamin B deficiency can lead to what?
Wernicke’s encephalopathy and Korsakoff’s psychosis
Hypercalcaemia effects
bone pain, stones, psychiatric issues
<= cincalcet
Pyridoxine may be needed in patients taking what drugs?
Isoniazid therapy
or penicillamine treatment in Wilson’s disease
Penicillamine is what kind of drug?
Chelating agent used for e.g. Wilson’s Disease, RA
Vitamin C deficiency can result in what condition?
Scurvy
What are the fat soluble vitamins?
ADEK
What are the water soluble vitamins?
B and C
Hypomagnesia effects
arrhythmias, hypokalaemia, hypocalcaemia
<= Mg salts
Vitamin D deficiency can result in what condition?
Rickets
In renal patients, why is alfacalcidol and calcitrol more appropriate for Vitamin D deficiency treatment over other Vitamin D replacement?
Vitamin D requires hydroxylation by the kidney to its active form, therefore the hydroxylated derivatives alfacalcidol or calcitriol should be prescribed if patients with severe renal impairment require vitamin D
If Vitamin D replacement is needed in severe renal impairment, what are the most appropriate to prescribe?
Alfacalcidol
Calcitriol
What is the water soluble Vitamin K preparation called?
Menadiol
What is the MHRA advice surrounding IV thiamine?
Risk of serious allergic reaction
Should be given over 30 mins
Facilities to treat anaphylaxis should be close by
Calcichew D3 is used for what?
Prevention + treatment of Vitamin D and Ca deficiency
What is cholecalciferol used for?
Prevention and treatment of Vitamin D deficiency
When would the higher dose of 5mg folic acid be recommended in pregnancy?
High risk of neural tube defects: Epilepsy Diabetes Sickle cell Previous infant with neural tube defect e.g. spina bifida
Otherwise the dose would be 400mcg folic acid daily
What is a Coombs test?
Test for autoimmune hemolytic anaemia
Methyldopa can cause a positive test result
What is the treatment regimen for hydroxocobalamin in the treatment of pernicious anaemia (without neurological involvement)?
What route?
IM injection
Initially 1 mg 3 times a week for 2 weeks, then 1 mg every 2–3 months.
If neurological involvement- this would be 1mg on alternate days until improvement
Iron absorption is impaired if having what foods/drinks?
Tea
Milk
Eggs
Rise in haemoglobin concentration takes about A. 2- 3 weeks B. 3- 4 weeks C. 1- 2 weeks D. 1 - 2 months
B 3-4 weeks
Rise in haemoglobin concentration takes about 3-4 weeks, treatment should be continued for a further 3 months to replenish the iron stores.
Parenteral iron may have serious hypersensitivity reactions. Incidents of anaphylaxis have been reported. In the event of a reaction, treatment should be
STOPPED IMMEDIATELY
drugs that may cause hypokalaemia (serum potassium concentration below 3.5 mmol/L)
Laxatives (excessive use) Diuretics ^dose beta 2 agonists Theophylline ^dose penicillins Gentamicin Amphotericin Echinocandin antifungals High dose insulin Corticosteroids Cisplatin Sodium bicarbonate Parecoxib
Medicines known to increase serum potassium levels
- Reduction of K renal excretion due to hypoaldosteronism:
Aldosterone antagonists: Spironolactone, eplerenone
ACEI: Captopril, enalapril, lisinopril
ARB: Candesartan, losartan
NSAIDs: Ibuprofen, naproxen, diclofenac, meloxicam
Heparins: Enoxaparin sodium
Immunosuppressive drugs: Cyclosporin, tacrolimus - Reduction of potassium passive renal excretion
K-sparing diuretics other than aldosterone antagonists: Amiloride, triamterene
Anti-infective drugs: Trimethoprim, pentamidine - Reduction of K cellular transport
Beta-blockers: Proprano, ateno, metoprolol, bisoprolol
Cardiac glycosides: Digoxin
Mood stabiliser: Lithium - Excess of potassium supply; salts; K chloride
- Unknown mechanism; Epoetin alfa, epoetin beta
Idiopathic thrombocytopenic purpura
Children@ self limiting
Adults: treat with corticosteroid (pred) gradually reducing dose over several weeks
If ineffective to achieve platelet count or relapse from reducing corticosteroid; splenectomy considered
Hyperphosphatemia imbalance effects
meds to treat?
Hyper (ectopic calcification, hyperparathyroidism)
aluminium hydroxide, Phosex, sevlamer
Hypophosphatemia imbalance effects
meds to treat?
Hypo (weak muscles, mental issues, blood disorder)
phosphate salts
Compensation for potassium loss is especially necessary
- in those taking digoxin or anti-arrhythmic drugs, where potassium depletion may induce arrhythmias;
- in patients in whom 2ndaryhyperaldosteronism occurs, e.g. renal artery stenosis, cirrhosis of the liver, the nephrotic syndrome, and severe heart failure;
- in patients with excessive losses of K in the faeces, e.g. chronic diarrhoea associated with intestinal malabsorption or laxative abuse.
- elderly; frequently take inadequate amounts of potassium in the diet
- long-term administration of drugs known to induce potassium loss (e.g. corticosteroids) long-term administration of drugs known to induce potassium loss (e.g. corticosteroids)
Are potassium supplements required with small doses of diuretics to treat HTN?
Are potassium supplements recommended for prevention of hypokalaemia due to diuretics?
Potassium supplements are seldom required with the small doses of diuretics given to treat hypertension;
K-sparing diuretics (rather than supplements) are recommended for prevention of hypokalaemia due to diuretics such as furosemide or the thiazides when these are given to eliminate oedema.
K salts cause n+v and poor compliance is a major limitation to their effectiveness; when appropriate, potassium-sparing diuretics are preferable.
Mild hyperkalaemia
Ion-exchange resins may be used to remove excess potassium in mild hyperkalaemia or in moderate hyperkalaemia when there are no ECG changes.
Oral rehydration therapy (ORT)
diarrhoea - most important indication for fluid and electrolyte replacement
Rehydration should be rapid over 3-4 hrs (except in hypernatraemic dehydration; slowly over 12 hours). Reassess after initial rehydration; if still dehydrated rapid fluid replacement should continue.
Once rehydration is complete further dehydration is prevented by encouraging the patient to drink normal volumes of fluid and by replacing continuing losses with an oral rehydration solution; in infants, BF or formula feeds should be offered between oral rehydration drinks.
hypokalaemia infusions
Potassium overdose can be fatal. Ready-mixed infusion solutions containing potassium should be used where possible. Potassium chloride solution for infusion must be given by slow intravenous infusion, under ECG control, ensuring adequate urine flow and with careful monitoring of electrolytes.
Rapid infusion can be toxic to the heart; cardiac
arrhythmias. Manufacturer recommendation is that the infusion rate should not exceed 20 mmol potassium per hour. A higher concentration and higher infusion rate may be given in severe potassium depletion under specialist
supervision.
Hyperkalaemia effects
Hypokalaemia effects
Fatigue, numbness, tingling, nausea or vomiting, trouble breathing, chest pain, irregular heart beat
constipation, irregular heartbeat, fatigue, muscle
damage, muscle spasms, tingling, numbness
drugs hyper K
drugs hypo K
ACE inhibitors; potassium supplements; NSAIDs; heparins; spironolactone; amiloride
Diuretics; beta-2 agonists, insulin; corticosteroids
Hyper Na
- symp
- drugs
- tx
Symptoms:
dehydration, thirst, osmotic damage of cells (confusion, muscle twitching or spasms, seizures)
Causative drugs
Corticosteroids; IV abx with Na; oral contraceptive; sodium bicarbonate
Treatment
Correction of the relative water deficit. If IV, administered via dextrose or saline infusion. Rapid correction can lead to cerebral oedema.
Hypo Na
- symp
- drugs
- tx
Symptoms
n+v, headache, confusion, fatigue, loss of appetite, irritability, osmotic damage of cells (confusion, muscle twitching or spasms, seizures)
Causative drugs
Anti-depressants; desmopressin; carbamazepine; diuretics; lithium
Treatment
Hypovolemia: IV saline
Euvolemic: fluid restriction & remove stimuli for ADH
Hypervolemic: address underlying heart or liver failure
Pyridoxne dose
Prolonged use of pyridoxine in a dose of 10 mg daily is considered safe but the long-term use of pyridoxine in a dose of 200 mg or more daily has been associated with neuropathy.
IV Thiamine
Rare risk of potentially serious allergic ADR, the CHM has recommended that:
• This should not prevent the use of parenteral thiamine in patients where this route of administration is required, particularly in patients at risk of Wernicke-Korsakoff syndrome where treatment with thiamine is essential;
• IV administration should be by infusion over 30 min;
• Facilities for treating anaphylaxis (including resuscitation facilities) should be available when parenteral thiamine is administered
