Wednesday [17/08/22] Flashcards
(28 cards)
Reference range for sodium [1]
135-145
reference range for potassium [1]
3.5-5
causes of hyponatraemia [7]
diuretics: thiazides, loop diuretics SIADH diarrhoea, vomiting, sweating IV dextrose, psychogenic polydipsia secondary hyperaldosteronism: heart failure, liver cirrhosis burns Addison's disease diuretic stage of renal failure hypothyroidism
Causes of hypernatraemia [4]
dehydration
osmotic diuresis e.g. hyperosmolar non-ketotic diabetic coma
diabetes insipidus
excess IV saline
Common causes of hyponatraemia [2]
Common
Thiaizide diuretics
Selective serotonin reuptake inhibitors
Less common causes of hyponatraemia [4]
Infrequent
Loop diuretics: side-effects
Lung cancer
Rare Sulfonylureas: side-effects Malaria (Falciparum) Addison's disease Legionella pneumonia Psittacosis Acute intermittent porphyria Carbamazepine
What are the pathways of coagulation? [3]
- Extrinsic
- Intrinsic
- Common pathways
All work together to form a blood clot
How do the extrinsic and intrinsic pathways work basically? [2]
The extrinsic and intrinsic coagulation pathways both lead into the final common pathway by independently activating factor X
Which factor does the extrinsic pathway work on? [1]
The extrinsic pathway involves initiation by factor III (i.e., tissue factor) and its interaction with factor VII.
Which factors does the intrinsic pathway work on? [1]
Whereas, factors XII, XI, IX, and VIII are utilized in the intrinsic pathway.
Which factors does the common pathway work on? [1]
Then, the common pathway uses factors X, V, II, I, and XIII.
When does the extrinsic pathway get activated? [2]
The extrinsic pathway begins when there is injury to the endothelial tissue (i.e., skin tissue), exposing tissue factor (factor III) to the blood. Tissue factor then becomes bound with calcium and factor VIIa to activate factor X. Factor VII is present in the blood and requires vitamin K to be activated.
When does the intrinsic pathway get activated? [2]
Meanwhile, the intrinsic pathway begins when factor XII or the Hageman factor is exposed to collagen, kallikrein, and high molecular weight kininogen (HMWK) and is subsequently activated. Factor XIIa activates factor XI into XIa. With a calcium ion, factor XIa activates factor IX. Then, factor IXa, factor VIIIa, and calcium form a complex to activate factor X. Factor VIII is found in the blood and is often activated by thrombin (factor IIa).
What happens at the common pathway? [2]
The common pathway may result after the activation of factor X at the end of either pathway. The common pathway begins when factor Xa, Va, and calcium bind together, forming a prothrombinase complex. The prothrombinase complex then activates prothrombin (factor II) into thrombin (factor IIa). Next, thrombin cleaves fibrinogen (factor I) into fibrin (factor Ia). Afterwards, thrombin cleaves the stabilizing factor (factor XIII) into XIIIa. Factor XIIIa binds with calcium to then create fibrin crosslinks to stabilize the clot. Thrombin has several functions, including activating platelets (cell fragments involved in clot formation) and activating factors V, VIII, and IX.
When is fibrin produced during the coagulation cascade? [2]
Fibrin (factor Ia) is a long, thin protein with branches produced at the end of the coagulation cascade when fibrinogen (factor I) is converted to fibrin, which stabilizes the blood clot.
What is the main goal of coagulation? [2]
The main goal of coagulation is to form a stable blood clot to stop bleeding and allow time for the tissue to be repaired.
Go through some common coagulation disorders [4]
Coagulation disorders are disorders which affect the coagulation cascade and can either cause excessive or inadequate clotting. Coagulation disorders usually involve a deficiency in at least one clotting factor, and the most common disorders include von Willebrand disease, hemophilia, and vitamin k deficiency.
Von Willebrand disease is the most common bleeding disorder and is characterized by a deficiency in von Willebrand factor due to an autosomal dominant genetic mutation. The von Willebrand factor is mostly involved in primary hemostasis where it helps platelets stick together. The factor also plays a role in secondary hemostasis by helping stabilize factor VIII.
There are three types of hemophilia that are caused by genetic mutations in clotting factor genes and can be passed on from parent to child. Hemophilia A is a deficiency in factor VIII, hemophilia B is a deficiency in factor IX, and hemophilia C is a deficiency in factor XI. All types of hemophilia affect the intrinsic pathway.
A vitamin K deficiency may occur when a sufficient amount of vitamin K is not absorbed from foods or when not enough foods with vitamin K are consumed (e.g., leafy dark green vegetables like spinach). Vitamin K is a cofactor required to make factors II, VII, IX, and X functional. Therefore, vitamin K deficiency affects all three pathways.
What are the most important facts to know about the coagulation cascade? [3]
The coagulation cascade refers to the series of steps that occur during the formation of a blood clot after injury by activating a cascade of proteins called clotting factors. There are three pathways: intrinsic, extrinsic, and common. The intrinsic pathway is activated by factors in the blood, while extrinsic is activated by tissue factor. Both pathways result in activation of factor X leading into the common pathway, which ends with converting fibrinogen into fibrin to form a stabilized blood clot. Coagulation disorders occur when there is a deficiency in a clotting factor involved, and the most common disorders are hemophilia and vitamin K deficiency.
What does the word haematinics mean? [2]
Haematinics are the nutrients needed by the bone marrow to make blood cells in the process of haematopoiesis. Without adequate amounts of these nutrients, cytopenia(s) and related symptoms can develop. Excess amounts can also be pathological and can point to various underlying disease states.
Vitamins involved in haematinics [7]
This guide to haematinics interpretation will focus on deficiencies of the most clinically relevant haematinics: vitamin B12 (cobalamin), vitamin B9 (folate), and iron.
Other haematinics not covered in this guide include:
Vitamin A Vitamin B2 (riboflavin) Vitamin B3 (nicotinic acid) Vitamin B6 Vitamin C Vitamin E Copper Cobalt
IDA iron in blood results
ferritin = low or normal
transferrin/TIBC = high
transferrin saturations = low
STFR = high/normal
acute=phase response iron studies
high ferritin
low transferrin/TIBC
anaemia of chronic disease iron studies
normal ferritin, normal/low transferrin/TIBC, normal/low transferrin saturations, normal STFR
Treatment of IDA [3]
Traditional dosing guidelines suggested aiming for 100-200mg of elemental iron a day however, more recent studies performed in iron deficient, non-pregnant women have shown that once-daily dosing of around 45-80mg elemental iron is more effective and avoids many of the gastrointestinal side effects. This amount of elemental iron roughly equates to one tablet of either ferrous fumarate 210mg or ferrous sulphate 200mg. A response in the haemoglobin count should be seen within a few weeks of starting therapy.
In certain scenarios, intravenous iron may be preferred. This includes patients with chronic kidney disease, inflammatory bowel disease, those intolerant of oral iron, those needing rapid replacement due to the degree of anaemia or certain pregnant patients. The safety profile has improved with more recent formulations but there is still a risk of anaphylactoid reactions and permanent skin staining.
