InfoLink Issue 5


*Issue 5 1999*

Margaret Hardy
Customer Relations Manager
Contact: 992-68574
Email: mhardy@doh.health.nsw.gov.au

I am Margaret Hardy and have recently joined the PaLMS Management Team as the Customer Relations Manager. I am a Registered Nurse with a Graduate Diploma in Nursing Management. My involvement with pathology commenced in 1972 and has included working in both the public and the private sectors. My area of expertise is specimen collection and I have been involved with the medical, nursing and scientific professions in education in relation to specimen collection for many years. I look forward to working with the Education Team in meeting the education needs of our customers.

I would also like to take this opportunity to thank Kerry Heintze for her contributions to InfoLink and the Education Team. Kerry is currently on maternity leave and we wish her well.

If you require the most up to date information about our collection centres or a comprehensive list of tests just visit the PaLMS Website www.palmslab.com.au it's worth the visit! If you don't have access to the Internet then make sure you have a copy of the PaLMS Service Directory fourth edition, a call to PaLMS Administration on 9926 8086 will ensure prompt delivery.

The new PaLMS request forms, which include collection centre details, are now available. These forms can be pre-printed with practitioners' details. Simply contact the PaLMS Service Centre on 9926 6066 to place your order.

In order for PaLMS to meet the needs of our customers we need to know what those needs are and I'm happy to visit your practice. So please get in touch with me so we can work together for the benefit of your patients. I can be contacted through PaLMS Administration 9926 8086.

LABORATORY INVESTIGATION OF THE SMALL, PALE RED CELL :
MICROCYTIC, HYPOCHROMIC ANAEMIA

Eva Raik
Haematology, PaLMS
Contact: tel +61 2 9926 7118
e-mail: eraik@ doh.health.nsw.gov.au

ANAEMIA- can be said to be present when there is a significant reduction of either or both the haemoglobin level and the total number of red cells below the lower level of the reference (normal) range for the gender and age of the individual. (For information about accessing PaLMS reference ranges .)
There are two physiological conditions which affect these parameters:

pregnancy, when the lower limit is reduced
prolonged stay at high altitude, when the lower limit is raised

It is worth noting that haemoglobin is measured as a concentration, consequently abnormal alterations in plasma volume (see Fig 1, next page) may affect the values obtained, eg dehydration, can mask the presence of anaemia as the haemoglobin (and red cell count) will be spuriously high and the opposite is seen in conditions such as cardiac failure when these levels appear too low.

MICROCYTOSIS - indicates that the red cell size (MCV) has fallen below the lower limit of the reference range . The acceptable lower limit of size is also age dependent, the limits normally being set by individual laboratories depending on the method used for cell sizing.

HYPOCHROMIA - is said to be present when individual red cells are insufficiently haemoglobinised. The mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration are measures of intracellular haemoglobin (see box, page 4). On the blood film the red cells only have a small rim of haemoglobin and are pale in appearance.

Disorders commonly associated with microcytosis and hypochromia are iron deficiency, the thalassaemias and the anaemia of chronic disease. Amongst the less common causes are lead poisoning, some sideroblastic anaemias and the presence of haemoglobin E.

DIAGNOSTIC ELEMENTS

Iron deficiency - remains the commonest form of anaemia world wide. The evaluation of an individual patient’s iron status should start with a comprehensive clinical history and physical examination. This, together with a full blood count (FBC) providing red cell indices and examination of the blood film may provide sufficient information to make a presumptive diagnosis of iron deficiency. Further laboratory investigation may not be required. Confirmation can be obtained by an appropriate response to oral iron therapy. IT IS, OF COURSE, IMPERATIVE that the cause of the iron deficiency is established and appropriately addressed. When confirmation of iron deficiency is required additional laboratory tests will assist in evaluation of iron status.

Additional laboratory investigations:

Serum ferritin estimation - the serum ferritin levels usually reflect iron stores, however ferritin is an acute phase reactant consequently the usefulness of the ferritin estimation is limited by the presence of inflammatory disease, hepatic and renal disease and neoplasia.
Serum iron and total iron binding capacity (transferrin) estimations. In uncomplicated iron deficiency the serum iron will be low and the iron binding capacity will be elevated.
Transferrin saturation may be more reliable than the individual measurements. Transferrin saturation of less than 15% is indicative of iron deficiency.
Bone marrow examination - may be required for definitive assessment of body iron stores.

Table 1 - Reference Ranges for Iron Studies

	MALE	FEMALE	CHILDREN
Iron	11-30 mmol/L	8-30 mmol/L
Total Iron Binding Capacity (Transferrin)	45-74 mmol/L	45-74 mmol/L	45-74 mmol/L
Ferritin	40-340 mg/L	15-150 mg/L	15-150 mg/L

A new diagnostic test on the horizon, not yet available routinely, is the assay of serum transferrin receptor. This can be expected to improve the detection of true iron deficiency and differentiate it from the anaemia of chronic disease. An increase in transferrin receptor provides a sensitive measure of iron deficiency as it reflects the total body mass of tissue receptor.

Free erythrocyte protoporphyrin, iron absorption studies and full ferrokinetics are rarely performed and are considered to be research tools.

Anaemia of chronic disease (ACD) whilst often normochromic and normocytic may also be hypochromic and/or microcytic. The iron stores may be normal or increased yet the developing red cells are unable to adequately utilise the iron. The microcytosis and/or hypochromia are usually not as marked as in i ron deficiency. It is important to remember that the ACD may co-exist with true iron deficiency. Serum iron and transferrin levels will be low with or without co-existent iron deficiency whilst the serum ferritin levels may be normal or elevated. However, serum ferritin levels below 50 g/L usually indicate the presence of iron deficiency. The assessment of bone marrow iron stores generally clarifies the situation.

The thalassaemic syndromes are usually recognised by microcytosis and hypochromia, often without significant anaemia in the heterozygous states. The red cell count is often higher relative to the haemoglobin value when compared to the corresponding haemoglobin due to iron deficiency. Other clues to the presence of a haemoglobinopathy may be evident from careful examination of the red cells in a well stained film. Nevertheless, the distinction between iron deficiency and the thalassaemias is often not readily apparent and can only be established by performing both iron and haemoglobin studies.

Table 2 - Comparison of Parameters for Microcytic, Hypochromic Anaemia

	Iron Deficiency	Thalassaemia	Anaemia or Chronic Disease	ACD plus Iron Deficiency
Haemoglobin	or N	or N
MCV			or N
Film	Microcytes Hypochromia	Microcytes Hypochromia	Microcytes +/- Hypochromia +/-	Microcytes Hypochromia
Iron		or N
Transferrin		N	or N
Transferrin % saturation		N	or N
Ferritin		or N	or N	or N
Bone marrow iron		or N	or N

For investigation of the rarer causes of microcytosis and hypochromia consultation with a specialist haematologist is recommended

Is This Result Normal?
PaLMS reference intervals can be accessed in a variety of ways:

On the NSH Intranet Site
- choose PaLMS
- click on test directory
- at the prompt, type in the name of the test
- select the test then specimen type
- in the left hand column, select "reference interval"
On the PaLMS Internet site.
- Visit our web site http://www.palms.com.au
- click on test directory
- at the prompt, type in the name of the test
- if necessary, use the scroll bar to scroll down to find a particular test (tests are listed in alphabetical order)
- select/click on the test then the specimen type in the right panel
- scroll down to the reference interval
From the PaLMS Service Directory.
- Contact PaLMS Administration on 9926 8086 if you would like us to send you a copy.
By telephoning the PaLMS Service Centre on 992 66066

Education Survey
The Education Team has recently surveyed PaLMS Pathologists and Senior Scientists in order to get an overview of educational and training activities occurring within PaLMS.
The response was most gratifying and the Education Team would like to thank all those who sent us details of their educational activities. As promised, surveys received before 7 December 1998 went into a draw for a bottle of wine. The winner was Professor Doug Saunders from FetoMaternal Medicine. Doug received a bottle of 1986 Wirra Wirra Chardonnay.