Question

1. Discuss the limitations of haematology reference ranges.

2. Discuss automated haematology analysers (Beckman Coulter haematology analyser) in detail.

Answer 1

2. Discuss automated haematology analysers (Beckman Coulter haematology analyser) in detail.

Hematology analyzers are used widely in patient and research settings to count and characterize blood cells for disease detection and monitoring. Basic analyzers return a complete blood count (CBC) with a three-part differential white blood cell (WBC) count. Sophisticated analyzers measure cell morphology and can detect small cell populations to diagnose rare blood conditions.

Hematology analyzer technology

The three main physical technologies used in hematology analyzers are: electrical impedance, flow cytometry, and fluorescent flow cytometry. These are used in combination with chemical reagents that lyse or alter blood cells to extend the measurable parameters. For example, electrical impedance can differentiate red blood cells (RBCs), WBCs, and platelets by volume. Adding a nucleating agent that shrinks lymphocytes more than other WBCs makes it possible to differentiate lymphocytes by volume.

Electrical impedance

The traditional method for counting cells is electrical impedance, also known as the Coulter Principle. It is used in almost every hematology analyzer.

Whole blood is passed between two electrodes through an aperture so narrow that only one cell can pass through at a time. The impedance changes as a cell passes through. The change in impedance is proportional to cell volume, resulting in a cell count and measure of volume.

Impedance analysis returns CBCs and three-part WBC differentials (granulocytes, lymphocytes, and monocytes) but cannot distinguish between the similarly sized granular leukocytes: eosinophils, basophils, and neutrophils.

Counting rates of up to 10,000 cells per second can be achieved and a typical impedance analysis can be carried out in less than a minute.

Flow cytometry

Laser flow cytometry is more expensive than impedance analysis, due to the requirement for expensive reagents, but returns detailed information about the morphology of blood cells. It is an excellent method for determining five-part WBC differentials.

A single-cell stream passes through a laser beam. The absorbance is measured, and the scattered light is measured at multiple angles to determine the cell’s granularity, diameter, and inner complexity. These are the same cell morphology characteristics that can be determined manually from a slide.

Fluorescent flow cytometry

Adding fluorescent reagents extends the use of flow cytometry to measure specific cell populations. Fluorescent dyes reveal the nucleus-plasma ratio of each stained cell. It is useful for the analysis of platelets, nucleated RBCs, and reticulocytes.

1. Discuss the limitations of haematology reference ranges.

Reference ranges for blood tests are sets of values used by a health professional to interpret a set of medical test results from blood samples.Reference ranges for blood tests are studied within the field of clinical chemistry (also known as "clinical biochemistry", "chemical pathology" or "pure blood chemistry"), the area of pathology that is generally concerned with analysis of bodily fluids.

Ions and trace metals

Test	Lower limit	Upper limit	Unit*	Comments
Sodium (Na)	135,[9] 137[4][10]	145,[4][10] 147[9]	mmol/L or mEq/L[9]	See hyponatremia or hypernatremia
310,[11] 320[11]	330,[11] 340[11]	mg/dL
Potassium (K)	3.5,[4][9] 3.6[10]	5.0,[4][9][10] 5.1	mmol/L or mEq/L[9]	See hypokalemia or hyperkalemia
14[12]	20[12]	mg/dL
Chloride (Cl)	95,[9] 98,[13] 100[4]	105,[9] 106,[13] 110[4]	mmol/L or mEq/L[9]	See hypochloremia or hyperchloremia
340[14]	370[14]	mg/dL
Ionized calcium (Ca)	1.03,[15] 1.10[4]	1.23,[15] 1.30[4]	mmol/L	See hypocalcaemia or hypercalcaemia
4.1,[16] 4.4[16]	4.9,[16] 5.2[16]	mg/dL
Total calcium (Ca)	2.1,[9][17] 2.2[4]	2.5,[4][17] 2.6,[17] 2.8[9]	mmol/L
8.4,[9] 8.5[18]	10.2,[9] 10.5[18]	mg/dL
Total serum iron (TSI) – male	65,[19] 76[10]	176,[19] 198[10]	µg/dL	See hypoferremia or the following: iron overload (hemochromatosis), iron poisoning, siderosis, hemosiderosis, hyperferremia
11.6,[20][21] 13.6[21]	30,[20] 32,[21] 35[21]	μmol/L
Total serum iron (TSI) – female	26,[10] 50[19]	170[10][19]	µg/dL
4.6,[21] 8.9[20]	30.4[20]	μmol/L
Total serum iron (TSI) – newborns	100[19]	250[19]	µg/dL
18[21]	45[21]	µmol/L
Total serum iron (TSI) – children	50[19]	120[19]	µg/dL
9[21]	21[21]	µmol/L
Total iron-binding capacity (TIBC)	240,[19] 262[10]	450,[19] 474[10]	μg/dL
43,[21] 47[21]	81,[21] 85[21]	µmol/L
Transferrin	190,[22] 194,[4] 204[10]	326,[4] 330,[22] 360[10]	mg/dL
25[23]	45[23]	μmol/L
Transferrin saturation	20[19]	50[19]	%
Ferritin – Males and postmenopausal females	12[24]	300[24][25]	ng/mL or µg/L
27[26]	670[26]	pmol/L
Ferritin – premenopausal females	12[24]	150[24] – 200[25]	ng/mL or µg/L
27[26]	330[26] – 440[26]	pmol/L
Ammonia	10,[27] 20[28]	35,[27] 65[28]	μmol/L	See hypoammonemia and hyperammonemia
17,[29] 34[29]	60,[29] 110[29]	μg/dL
Copper (Cu)	70[18]	150[18]	µg/dL	See hypocupremia or hypercupremia
11[30][31]	24[30]	μmol/L
Ceruloplasmin	15[18]	60[18]	mg/dL
1[32]	4[32]	μmol/L
Phosphate (HPO42−)	0.8	1.5[33]	mmol/L	See hypophosphatemia or hyperphosphatemia
Inorganic phosphorus (serum)	1.0[9]	1.5[9]	mmol/L
3.0[9]	4.5[9]	mg/dL
Zinc (Zn)	60,[34] 72[35]	110,[35] 130[34]	μg/dL	See zinc deficiency or zinc poisoning
9.2,[36] 11[4]	17,[4] 20[36]	µmol/L
Magnesium	1.5,[18] 1.7[37]	2.0,[18] 2.3[37]	mEq/L or mg/dL	See hypomagnesemia or hypermagnesemia
0.6,[38] 0.7[4]	0.82,[38] 0.95[4]	mmo

Test	Arterial/Venous	Lower limit	Upper limit	Unit
pH	Arterial	7.34,[10] 7.35[9]	7.44,[10] 7.45[9]
Venous	7.31[40]	7.41[40]
[H+]	Arterial	36[9]	44[9]	nmol/L
3.6[41]	4.4[41]	ng/dL
Base excess	Arterial & venous[40]	−3[40]	+3[40]	mEq/L
Oxygen partial pressure (pO2)	Arterial pO2	10,[9] 11[42]	13,[42] 14[9]	kPa
75,[9][10] 83[18]	100,[10] 105[9]	mmHg or torr
Venous	4.0[42]	5.3[42]	kPa
30[40]	40[40]	mmHg or torr
Oxygen saturation	Arterial	94,[40] 95,[13] 96[18]	100[13][18]	%
Venous	Approximately 75[13]
Carbon dioxide partial pressure (pCO2)	Arterial PaCO2	4.4,[9] 4.7[42]	5.9,[9] 6.0[42]	kPa
33,[9] 35[10]	44,[9] 45[10]	mmHg or torr
Venous	5.5,[42]	6.8[42]	kPa
41[40]	51[40]	mmHg or torr
Absolute content of carbon dioxide (CO2)	Arterial	23[40]	30[40]	mmol/L
100[43]	132[43]	mg/dL
Bicarbonate (HCO3−)	Arterial & venous	18[18]	23[18]	mmol/L
110[44]	140[44]	mg/dL
Standard bicarbonate (SBCe)	Arterial & venous	21, 22[9]	27, 28[9]	mmol/L or mEq/L[9]
134[44]	170[44]	mg/dL

Liver function

Liver function tests

Test	Patient type	Lower limit	Upper limit	Unit	Comments
Total protein (TotPro)		60,[9] 63[10]	78,[9] 82,[10] 84[18]	g/L	See serum total protein Interpretation
Albumin		35[9][45]	48,[10] 55[9]	g/L	See hypoalbuminemia
3.5[10]	4.8,[10] 5.5[9]	U/L
540[46]	740[46]	μmol/L
Globulins		23[9]	35[9]	g/L
Total bilirubin		1.7,[47] 2,[9] 3.4,[47] 5[4]	17,[9][47] 22,[47] 25[4]	μmol/L
0.1,[9] 0.2,[10] 0.29[48]	1.0,[9][18] 1.3,[10] 1.4[48]	mg/dL
Direct/conjugated bilirubin		0.0[9] or N/A[4]	5,[9] 7[4][47]	μmol/L
0[9][10]	0.3,[9][10] 0.4[18]	mg/dL
Alanine transaminase (ALT/ALAT[4])		5,[49] 7,[10] 8[9]	20,[9] 21,[13] 56[10]	U/L	Also called serum glutamic pyruvic transaminase (SGPT)
Female	0.15[4]	0.75[4]	µkat/L
Male	0.15[4]	1.1[4]
Aspartate transaminase (AST/ASAT[4])	Female	6[50]	34[50]	IU/L	Also called serum glutamic oxaloacetic transaminase (SGOT)
0.25[4]	0.60[4]	µkat/L
Male	8[50]	40[50]	IU/L
0.25[4]	0.75[4]	µkat/L
Alkaline phosphatase (ALP)		0.6[4]	1.8[4]	µkat/L
Female	42[49]	98[49]	U/L
Male	53[49]	128[49]
Gamma glutamyl transferase (GGT)		5,[49] 8[10]	40,[49] 78[10]	U/L
Female		0.63[51]	µkat/L
Male		0.92[51]	µkat/L

Cardiac tests

Test	Patient type	Lower limit	Upper limit	Unit	Comments
Creatine kinase (CK)	Male	24,[52] 38,[10] 60[49]	174,[18] 320[49]	U/L or ng/mL
0.42[53]	1.5[53]	µkat/L
Female	24,[52] 38,[10] 96[18]	140,[18] 200[49]	U/L or ng/mL
0.17[53]	1.17[53]	µkat/L
CK-MB		0	3,[10] 3.8,[4] 5[49]	ng/mL or μg/L[4]
Myoglobin	Female	1[54]	66[54]	ng/mL or µg/L
Male	17[54]	106[54]
Cardiac troponin T			0.01[55]	ng/mL	99th percentile cutoff

Brain natriuretic peptide (BNP) -more detailed ranges in BNP article
Interpretation	Range / Cutoff
Congestive heart failure unlikely	< 100 pg/mL[56][57]
"Gray zone"	100-500 pg/mL[56][57]
Congestive heart failure likely	>500 pg/mL[56][57]

NT-proBNP -more detailed ranges in NT-proBNP article
Interpretation	Age	Cutoff
Congestive heart failure likely	< 75 years	> 125 pg/mL[58]
>75 years	>450pg/mL[58]

Lipids

Blood lipids

Test	Patient type	Lower limit	Upper limit	Unit	Therapeutic target
Triglycerides	10–39 years	54[18]	110[18]	mg/dL	< 100 mg/dL[59] or 1.1[59] mmol/L
0.61[60]	1.2[60]	mmol/L
40–59 years	70[18]	150[18]	mg/dL
0.77[60]	1.7[60]	mmol/L
> 60 years	80[18]	150[18]	mg/dL
0.9[60]	1.7[60]	mmol/L
Total cholesterol		3.0,[61] 3.6[9][61]	5.0,[4][62] 6.5[9]	mmol/L	< 3.9 mmol/L[59]
120,[10] 140[9]	200,[10] 250[9]	mg/dL	< 150 mg/dL[59]
HDL cholesterol	Female	1.0,[63] 1.2,[4] 1.3[61]	2.2[63]	mmol/L	> 1.0[63] or 1.6[61]  mmol/L 40[64] or 60[65] mg/dL
40,[64] 50[66]	86[64]	mg/dL
HDL cholesterol	Male	0.9[4][63]	2.0[63]	mmol/L
35[64]	80[64]	mg/dL
LDL cholesterol (Not valid when triglycerides >5.0 mmol/L)		2.0,[63] 2.4[62]	3.0,[4][62] 3.4[63]	mmol/L	< 2.5 mmol/L[63]
80,[64] 94[64]	120,[64] 130[64]	mg/dL	< 100 mg/dL[64]
LDL/HDL quotient		n/a	5[4]