COMPARISON OF PHOTOMETRIC CYANMETHEMOGLOBIN AND AUTOMATED METHODS FOR HEMOGLOBIN ESTIMATION
Azim, *Shahida Parveen, Saadat Parveen
of Pathology, Combined Military Hospital, Multan and *CPC Research Projects DG
Hemoglobin estimation is the most frequent laboratory investigation requested.
Different methods include acid haematin, photometric cyanmethemoglobin
estimation and automated estimation with the help of counters. Aims and
objectives of the current study were to compare photometric cyanmethemoglobin
method with hemoglobin estimation by Medonic automated counter. Methods:
One hundred and ten adult cases were included through convenience sampling.
Samples with hemolysis were excluded from the study. Blood was drawn in CP
bottles. Sample was thoroughly mixed and hemoglobin estimation was done by
Medonic counter as well by photometer 4010. Commercial controls were run with
each batch. Results: By manual
methods, results revealed mean 0.85% increase compared to automated counter.
Commercial control results showed 2.3% and 2.7% coefficient of variation by
Medonic counter and photometer 4010 respectively. Conclusions:
It was concluded that both methods are accurate and precise, with reference
range 2.61% more in manual method. It is recommended that with small samples
and with parameters like hemoglobin or hemoglobin with erythrocyte
sedimentation rate, manual method is cost effective and feasible. However with
multiple parameters like absolute values and with very large batches, like in
tertiary laboratory, automated method is time effective and feasible, provided
the laboratory can bear the cost.
estimation, Cell counter, Cyanmethemoglobin.
(Hb) is a porphyrin iron protein compound that transports oxygen from the
lungs to the body tissues where it is utilized for energy metabolism1.
Hemoglobin estimation is of prime importance in medical investigations. It is
advised in every admitted case and in all the females undergoing antenatal
being initial and most commonly advised test in laboratory diagnostic
analysis, needs a most suitable and economical method of estimation. Different
methods are in use like acid hematin method, cyanmethemoglobin method by
photometer and automated methods by cell counters2. Different
laboratories need different methods depending upon number of patients,
technical skill of staff and availability of funds. Cost effective method
which is accurate and precise is required by the all the laboratories3.
Aims and objectives of the study were to evaluate the precision, accuracy, suitability, cost effectiveness and feasibility of photometric versus automated method of Hb estimation.
adult patients recommended for Hb estimation by out patient clinics and wards
of CMH Multan were included in the study. Ten patients were selected on
alternate day and a total of 11 batches were made. Samples with hemolysis were
excluded from the study. Samples were divided into batches of 10 samples per
batch. Blood samples were drawn in CP bottles, having K3 EDTA
anticoagulants. After proper mixing hemoglobin was estimated by automated
Medonic cell counter. Parallel estimation for Hb content was done manually by
spectrophotometer 4010. Ten µL of well mixed blood sample was taken in 2 ml
of Drabkin’s reagent and incubated at 37 °C for 10 minutes. Absorbance was
taken at 540 nm 4. PARA-12 commercial control was also run with
each batch. Accuracy, precision and cost of both the methods were compared on
SPSS computer software.
method on Medonic CA 530 is based on electronic impedance principle for cell
counting while lysing and colorimetry for Hb estimation. In manual method, Hb
in the sample reacts with Drabkin’s reagent to from cyanmethemoglobin, which
is estimated photometrically at 540 nm with the help of standard Hb solution5.
total of 110 samples were estimated for hemoglobin estimation. Out of these 62
were males and 36 females. Mean hemoglobin concentration on Medonic automated
analyzer was 11.7 mg/dL ±
2.59, while mean hemoglobin concentration by cyanmethemoglobin method on
photometer on 4010 was 11.8 mg/dL ±
2.39. This showed 0.85% increase in results by manual method. Commercial
control results were within the control range by both the methods. Comparison
of different variables by both methods is given in table 1.
of automated analysis was Rs. 50/test, while manual method costed Rs.
3.5/test. It takes 5 minutes by Medonic counter compared to 25 minutes by
manual method. Maintenance of automated analyzer caused frequent problems,
while photometer 4010 required negligible maintenance.
Table-1: Comparison of Medonic counter and photometer 4010.
of variation of controls
tertiary care medical unit of public as well as private sector needs an
economically suitable methodology. Automated cell counter costs Rs. 50/sample
for hemoglobin estimation while cyanmethemoglobin method performed manually
costs a few rupees only. Cost of Medonic Cell Counter is about Rs. 0.65
million while cost of photometer 4010 is about Rs. 0.22 million. As photometer
4010 has the capability to do all the chemistry analytes, so separate
photometer for Hb is not required in small laboratories. So it is recommended
that for single test advice, manual estimation being accurate and cost
effective should be preferred. Automated estimation, no doubt, is feasible,
but should be carried out when the whole blood picture and red cell indices
are required. Before the advent of automation, salicylic acid haematin method
used to be compared with colorimetric cyanmethemoglobin method6.
Now with increasing automation and increased requests for Hb estimation,
comparison was required for suitability of different labs, according to their
workload, staff and available equipment available in the lab7. US
Lab accreditation programmes have set up quality goals for both the methods
and set up standards to follow, which should be followed8. Both
methods can be monitored by proper quality control and can be adopted with
accuracy and precision9. A periodic scheme for evaluation of
methods being run by the labs should be followed for continued improvement10.
is concluded that proper feasibility and evaluation should be done before
adopting a method and within approved feasibility, both methods can prove to
be accurate and precise. A tertiary laboratory should have both methods while
small laboratory may give equally good results with photometer 4010.
EN. Erythropoiesis. In: Foester J, Paraskevas F, Grear JP, Rodgers GM, eds.
Wintrobes clinical hematology. Williams Wilkins, Baltimore 1999; 169-227.
Munawar F. Hemoglobin levels in day scholars and boarders of Fatima Jinnah
Medical College. Pakistan J M Res 1997; 36(3): 113-4.
VF, Klee GG. Biochemical aspects of hematology. In: Burtis CA, Ashwood ER.
Teitz textbook of clinical chemistry. WB Saunders Company, Philadelphia 1999;
Bates I. Basic hematological techniques. In: Lewis SM, Bain BJ, Bates I, eds.
Dacie & Lewis Practical hematology. Churchil Livingstone, Edinburg 2001;
HR. Examination of blood. In: Beutler E, Lichtman MA, Coller BS, Kipps TJ,
Seligsolin URI, eds. Williams Hematology sixth edition. McGraw Hill Medical
Publishing Division 2001; 9-16.
HJ. Comparative study of Sahli’s and Cyanmethemoglobin methods of hemoglobin
estimation. Pakistan J Med Res 1999; 38(4): 149-50.
M. District Laboratory Practice in tropical countries. Cambridge University
Press 2000; 267-347.
section 2. The College of American Pathologists (CAP) Laboratory Accreditation
Program checklists, 2000
Lehman CA, Leiken AM. Clinical laboratory instrumentation and automation:
Principles, application and selection.
Philadelphia: WB Saunders Company 1994.
Address for Correspondence and Reprints:
Lt. Col Dr Waqar Azim,
88, St-29, Sector I-9/1, Islamabad. Pakistan.