Nota Perubatan

Category: Laboratory

  • Renal Profile (RP) & BUSE

    Urea-Creatinine Ratio

    Sometimes, you might be able to suspect upper GI Bleed from RP, if patient has sudden anaemia (Hb drop)!

    This first thing that you will do when there is significant Hb drop is doing a Per Rectal Examination to look for melaena

    You might need to take RP & coagulation profile, together with PR finding then you refer Surgical / Gastro team for OGDS

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    Urea: 3.1 – 9.1 mmol/L
    Creat: 60 – 100 micromol/L = (0.06 – 0.1 mmol/L)

    Normal ratio of urea-creatinine ratio is 40 – 100:1 (make urea & creatinine in similar unit, i.e. mmol/L)

    Example: When urea is 2.5, estimated creatinine should be about 2.5 ÷ 40 = 0.0625 mmol/L , i.e. 62.5 micromol/L

    When urea is 14, estimated creatinine should be about 350 micromol/L (14 ÷ 40 × 1000)

    However, urea is considered relatively high if urea is 14, while creatinine is only 120 (14 ÷ 0.12 = 116, i.e. >100:1)

    Further reading: https://litfl.com/urea-creatinine-ratio/

    Miscellaneous

  • Blood Gas — Arterial Blood Gas (ABG) & Venous Blood Gas (VBG)

    Equipment

    Have you seen this syringe before? This is not a normal 1 cc syringe, but this is a heparin-prefilled 1 cc syringe, for blood gas samples. With this syringe, we don’t need to coat the wall of syringe with heparin manually.

    PS: not all hospital / all departments have this priviledge

    Sampling

    How to use a blood gas analyser?

    • Sometimes, as MO / HO, we have to run the blood gas by ourselves, especially in NICU / labour room / ED (some hospitals only allow certain staff to operate those machines as those machines can get spoilt easily if not handled properly)
    • The video shows how a blood gas analyser machine works in general. If you notice, it only uses a little of blood, the remaining is not required. Usually I only send about 0.5 mL of blood to lab for ABG / VBG. You don’t need to fill up the whole 1.0 mL syringe to get blood gas result, if your ice is not enough, the blood at the top part will clot, then you have to retake the blood gas.
    • If you are not sure how to run the machine, ask for help, don’t do it alone.

  • Reticulocytes

    Introduction

    Reticulocytes are young, larger red blood cells (contain RNA) signifying active erythropoiesis

    Normal Range

    0.8 – 2%

    Causes of raised reticulocytes count

    • Haemolysis (Examples: severe NNJ due to ABO incompatibility, other forms of haemolytic anaemia in adults)
    • Haemorrhage
    • B12 / folate / iron given to bone marrow that lack these vitamins

  • Common Workups

    WorkupItem

    Anaemic workup

    – FBC
    – FBP
    – Iron studies (Serum iron, ferritin, UIBC, TIBC, TSAT)
    – Vitamin B12, Folate (Indicated if the anaemia is macrocytic)

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    Sometimes in patients with underlying autoimmune disease / haemolytic anaemia is suspected, further test should also be sent. Haemolytic workup:
    – Reticulocyte count
    – LFT (bilirubin, especially indirect bilirubin would be raised) 
    – LDH
    – Coombs test
    – Coagulation profile 

    Note: Send these BEFORE first transfusion if possible, otherwise the report will not be accurate

    Hepatitis screening

    Usually we send: 
    – HBsAg
    – Anti-HCV

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