The Collison Newsletter September 2009

 

FBC, ESR, LFT, TSH - What Do These Mean?* 

 

The FBC, ESR, LFT and TSH are four of the most commonly ordered pathology tests. A frequently asked question is “What do these mean?”.

They are the shorthand of doctors and, in particular, pathologists. Shorthand is just what it says… it saves writing and, by using acceptable abbreviations, clearly communicates. The referring doctor just writes these letters on the referral form and the pathologist knows what tests are requested. When you read the form on the way to the pathologist’s rooms, you do not know what has been asked for, or for that matter probably, why!  There are many other groupings of letters that are routinely used, which will not be discussed here.

All normal ranges in this newsletter are from Southern.IML Pathology.

FBC 

This stands for Full Blood Count.

 

In this test, the cells in the blood are examined. The pathologist’s report sets out the numbers of the different types and their characteristics. It is sometimes called a differential blood count.

Red Blood Cells 

These are also called erythrocytes.

 

Hb is Haemoglobin. This is the main substance in the red cells. It carries oxygen. When saturated with oxygen it is a bright red colour, which gives the colour to arterial blood. The normal range is 130-180 g/L.

 

 

RCC is the Red Cell Count. The number of red cells in a cubic millimetre of blood should be 4.3 million – 6.0 million. Multiple characteristics of the red cells are noted, again with letters. For example, MCHC stands for mean corpuscular haemoglobin content, and MCV stands for the mean corpuscular volume. The size of the cells and their shape are also documented, again with letters.

White Cells

WCC is the total White Cell Count, again as found in one cubic millimetre of blood. The normal range is 4,000–11,000.

 

There are many different types of white cells, and these subgroups are also counted and reported. These include neutrophils, lymphocytes (with many types), monocytes, eosinophils and basophils. All these have special functions. The most common are the neutrophils (normal range 2,000-7,500) and the lymphocytes (normal range 1,000-4,000).

 

Platelets are another type of small white cell, involved with the clotting process. The normal range is 150,000–450,000.

ESR 

This stands for Erythrocyte Sedimentation Rate.

 

When a column of blood is allowed to stand for one hour, there should be very little settling of the red cells or erythrocytes. They remain suspended. The amount they settle is the ESR. It is measured in millimetres per hour. The ESR should not exceed 15 mm/hr. It is elevated in many disease states, but is not diagnostic.

LFT  

This stands for Liver Function Tests.

 

The liver is a highly complex organ in which hundreds of chemical events take place every second. When the doctor wants an assessment of overall hepatic or liver function, LFT’s are ordered.

 

Three functions of liver activity are generally measured:

·       Excretion

·       Manufacture

·       Cellular turnover.

 

Bilirubin is a breakdown product from haemoglobin and is excreted by the liver. Its level in the blood gives an accurate measure of the liver’s ability to excrete. The serum bilirubin should not exceed 20 umol/L.

 

Total protein, albumin and globulin levels in the blood reflect the liver’s manufacturing ability. The normal range for serum total protein is 63-80 g/L, for albumin is 37-50 g/L and for globulin is 20-36 g/L.

 

Liver enzymes. The trillions of cells throughout the body are constantly dying and being replaced. This cellular turnover is not apparent to us. For example, the red cells in the blood are totally replaced every four months. This process is also taking place in the liver. Because of the special functions of the liver, the liver cells contain unique enzymes, and when a cell dies, the enzymes in it are liberated and can be measured in the blood. The levels of these enzymes are elevated when there is an increase in the death or turnover of the liver cells, as occurs in hepatitis and in poisoning by excess alcohol, drugs or other poisons. For example, an overdose of paracetamol kills by destroying or poisoning the liver.

 

The following enzymes are measured in LFTs:

ALP:   Alkaline Phosphatase (normal range 25-110 U/L)

GGT:  Gamma Glutamic Transpeptidase (normal range 10-49 U/L)

ALT:   Alanine Transaminase (normal range 5-40 U/L)

AST:   Aspartate Transaminase (normal range 5-40 U/L)

LDH:   Lactate Dehydrogenase (normal range 100-310 U/L).

TSH 

This stands for Thyroid Stimulating Hormone.

 

This is one of the blood tests looking at the function of the thyroid gland. TSH is produced by the pituitary gland, a small but vitally important gland at the base of the skull, on the underside of the brain. The pituitary gland also produces and secretes into the blood stream a number of other hormones. TSH travels via the blood stream to the thyroid gland where it stimulates the gland to produce and secrete into the blood stream thyroid hormone which controls the metabolic activity of the body.

 

The normal range for TSH is 0.30-5.00 mU/L.

   

  

FBC, ESR, LFT and TSH are measured from a sample of blood taken from you at the pathologist’s laboratory and the report is sent to the referring doctor.

  

*Copyright 2009: The Huntly Centre.

  

Disclaimer: All material in the Huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.

  

    

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