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Year : 2013 | Volume : 1 | Issue : 1 | Page : 27 - 29  


Short Communications
Study of Reticulocyte count and Thyroid Hormones in Hypothyroidism in children and adults

B. Kusumakumari1, V. Devendar Reddy2, Indira Naik3

1 Professor and Head of Physiology, Malla Reddy Institute of Medical Sciences, Hyderabad. 2 Professor and Head of Physiology, Deccan College of Medical Sciences, Hyderabad. 3X - Professor and Head of Physiology, Gandhi Medical College, Hyderabad.

Summary

Hypothyroidism in the young child and neonate is an urgent situation as proper development of neural tissue in early life requires adequate levels of thyroid hormones. Deficiency can cause severe irreversible mental, physical handicaps-cretinism. Therefore an early diagnosis and treatment is very essential by neonatal screening for this disorder worldwide. The Objectives was to study the importance of reticulocyte count and to evaluate various parameters like T3, T4 and TSH in the hypothyroid cases. 14 cases and 9 controls in the pediatrics age group and 19 cases and 6 controls in the adult age group were studied. Both cases and controls were subjected to investigations like T3, T4 and TSH, Reticulocyte count and Hemoglobin. Statistical analysis was done using mean and standard deviation. Mean difference was tested using student ‘t’ test and with and without log transformations. The values of the T4 levels in the hypothyroid cases recorded was 2.53+4.4 mcg/dl which was moderately significant when compared to the controls who had values of 6.31+1.09 (p < 0.05). Similarly TSH values were also high with values of 63.61+46.53 microunits/ml which was found to be more significant than control who had low levels of 3.15+1.58 (p < 0.01). Reticulocyte counts in the pediatric cases of hypothyroidism showed low values of 0.63+0.27% which was highly significant to that of controls with values of 1.19+0.46% (p < 0.01). Reticulocyte count can be used as an alternate economical and accessible indicator in knowing the prognosis of hypothyroidism.

Key words: hypothyroidism, reticulocyte count, thyroid hormones

Corresponding Author: Dr. B. Kusumakumari; MD (Physiology); Professor and Head, Department of Physiology, Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad

Email: ksmkmr4@gmail.com


Introduction:

Hypothyroidism is normally defined as a thyroid stimulating hormone level elevated above the reference range with low T4, probably affects hundreds of thousands of people without being diagnosed.

Disorders of the thyroid gland are frequently encountered in childhood and adolescence. Thyroid hormones affect every organ system in most processes in the body through their action on the metabolism of energy substrates, nutrients and inorganic ions. During the first two decades of life, thyroid gland has an immense influence on physical growth, development and nutrition. Thyroid hormones play a crucial role in fetal and early postnatal brain development. [1]

Hypothyroidism in the young child particularly the neonate is truly an urgent situation. Deficiency can cause severe irreversible mental, physical handicaps-cretinism. The major part of brain development i.e. 90% occurs during the first two years of life. [2]

Thyroxine and cortisone have been considered to stimulate erythropoiesis because reticulocytosis may follow their administration. [3] Erythropoietin secretion is reduced in hypothyroid patients and thyroidectomised animals. Thyroid hormones, however, may have direct effect on erythropoiesis. [4] Reticulocyte count is an extremely valuable index as it provides a ready means of assessing rate of Red Blood Cells (RBC) production. [5] Therefore an early diagnosis and treatment is very essential by neonatal screening for this disorder worldwide. Based on the above information, the present study has been planned with the objectives to study the importance of reticulocyte count and to evaluate various parameters like T3, T4 and TSH in the hypothyroid cases.

Methods:

The study was conducted at the Endocrinology department of Gandhi Medical College, Hyderabad. Institutional Ethics Committee Permission was obtained. It was planned to conduct the study in two groups of patients i.e. adults and children. The study period was one year. During this period, it was possible to study only 14 cases of hypothyroidism among children and 19 cases in adults. Informed consent was obtained from patients in case of adults and from parents in case of children. The study design was cross sectional with comparison group. The study consisted of cases and controls. Cases were defined as patients who were showing signs and symptoms of hypothyroidism and were confirmed by thyroid profile. Controls were defined as those patients who were not showing signs and symptoms of hypothyroidism and whose thyroid profile was normal.

Only those cases and controls were included who consented to participate in the study during the study period. In this way it was possible to include 14 cases and 9 controls in the pediatrics age group and 19 cases and 6 controls in the adult age group.

Both cases and controls were interrogated in the same manner and the information was included in the pre designed questionnaire. Both cases and controls were subjected to investigations like T3, T4 and TSH, Reticulocyte count and Hemoglobin.

Serum T3, T4 and TSH were measured by radio immune assay (RIA). The basis of RIA is by competitive inhibition of binding of labeled hormone to antibody by unlabelled hormone contained in standard or in unknown samples. In endocrinology laboratory the Immune Radio Metric Assay (IRMA) kit for TSH (IRMAK-9). RIA kit for Thyroxine is (RIAK – 5/5A). IRMAK – 9, IRMA kit for small human TSH (h-TSH), is specifically designed to Quantitative human TSH in serum or plasma sample. [6]

Hemoglobin was measured by Sahli’s methods. [7]

Reticulocyte count was done by collecting a drop of blood from the heel of the newborn babies and from the index finger in case of older children and adults. Reticulocyte count was done following the standard procedure. [8] Heart rate was measured by taking radial pulse. All the patients of hypothyroidism were given appropriate treatment after the blood samples were collected. They were new cases and not on treatment at the time of the study. But later on treatment was started for them. Statistical analysis was done using mean and standard deviation. Mean difference was tested using student‘t’ test (unpaired) and with and without log transformations.

Results:

A total of 48 subjects were selected for the study. They were classified into two different groups i.e. pediatric and adults. Out of 48, there were 23 in the pediatric while adults were 25. Bothe the sexes were included in the study. In the pediatric group, their age ranged from 0 – 14 years and in the adult, it was from 18 – 70 years.

 

Table 1: Values of T3, T4 and TSH by groups in children

 

Category               N             T3 (ng/dl)              T4 (microgm/dl)   TSH (microunits/ml)

                                           (mean+SD)           (mean+SD)           (mean+SD)

Cases                     14           0.54+0.65              2.53+4.4             63.61+46.53

Controls                  09           0.79+0.21              6.31+1.09              3.15+1.58

P value                                   p > 0.05                 p < 0.05                 p < 0.001

N = total number

 

Table 1 shows the values of the T4 levels in the hypothyroid cases in children recorded as 2.53+4.4 mcg/dl which was moderately significant when compared to the controls who had values of 6.31+1.09 (p < 0.05). Similarly TSH values were also high with values of 63.61+46.53 microunits/ml which was found to be more significant than control who had low levels of 3.15+1.58 (p < 0.01). However there was no significant difference in the T3 values in the same subjects studied.

 

Table 2: Values of reticulocyte count, hemoglobin and heart rate by groups in children

 

Category               N             Reticulocyte count (%)       Hb%                                 Heart rate/min

                                                (mean+SD)                 (mean+SD)                         (mean+SD)

Cases                     14           0.63+0.27**                    10.20+1.37                           91.61+32.31

Controls                  09           1.19+0.48                        10.57+2.48                           97.00+21.72

P value                                   p < 0.01                            p > 0.05                              p > 0.05

N = total number

 

Table 2 shows that the Reticulocyte counts in the pediatric cases of hypothyroidism showed low values of 0.63+0.27% which was highly significant to that of controls with values of 1.19+0.46% (p < 0.01). However hemoglobin and heart rate did not reveal any significant difference in their values with respect to controls.

The mean values of T3, T4 and TSH of adult cases and controls are depicted in table 3. The T4 values in this group recorded low with mean values of 0.72+1.20 mcg/dl which was highly significant when compared to controls who had normal mean values of 7.76+2.28 (p < 0.001). Similarly TSH values were abnormal with high mean values of 46.56+15.83 microunits/ml which was also highly significant when compared to the controls who had 2.83+3.98 (p < 0.001). However the T3 values in these subjects showed moderately significant values of 0.33+0.25 in comparison to the controls with mean values of 0.89+0.25 nanogm/dl (p < 0.01).

 

Table 3: Values of T3, T4 and TSH by groups in adults

 

Category                   N             T3 (ng/dl)              T4 (microgm/dl)            TSH (microunits/ml)

                                               (mean+SD)              (mean+SD)                      (mean+SD)

Cases                        19           0.33+0.25              0.72+1.20*                           46.56+15.83**

Controls                     06           0.89+0.25              7.76+2.28                              2.83+3.98

P value                                       p > 0.05                 p < 0.01                            p < 0.001                              

N = total number

 

Table 4: Values of reticulocyte count, hemoglobin and heart rate by groups in adults

 

Category               N             Reticulocyte count (%)              Hb%                              Heart rate/min

                                                (mean+SD)                       (mean+SD)                        (mean+SD)

Cases                     19           0.56+0.41**                         11.76+6.34                           82.11+6.34

Controls                  06           0.77+0.40                            12.17+0.29                           80.67+1.16

P value                                   p < 0.001                               p > 0.05                                p > 0.05

N = total number

 

Table 4 shows that the values of Reticulocyte counts in terms of percentage where the adult subjects had recorded low values of 0.56+0.41% which was highly significant in comparison to the controls who had high values of 0.77+0.40% (p < 0.001). There was no statistical difference in the hemoglobin and heart rate values of the adult hypothyroid cases.

Discussion:

T4 value in 0 – 14 years of age group subjects was lower among cases (2.53+4.4 mcg/dl) when compared to controls who showed 6.31+1.09. Simultaneously the TSH values showed significant increase i.e. 63.61+46.53 microunits/ml, when compared to controls which is 3.15+1.58 microunits/ml. Similar findings were reported by Roger AB et al. [9]

The RIA for thyroid hormones and TSH have simplified the early diagnosis of congenital hypothyroidism. By this RIA the diagnosis is now possible at birth from cord blood studies in asymptomatic newborns. The possibility of in-utero diagnosis in selected cases by estimating the amniotic fluid RT3 or by obtaining blood sample by cordocentesis is also there. Subnormal levels of serum T3 and T4 and elevated TSH establish the diagnosis of primary hypothyroidism.

In these cases, the Reticulocyte count showed significant lower values when compared to controls which are indicative of anaemia due to suppression of erythropoiesis in hypothyroid cases. [10]

The reticulocyte count is a fairly accurate reflection of erythropoietic activity assuming that the reticulocytes are released normally from the bone marrow. [3] It is a primary condition for using reticulocyte investigations as a relatively exact measure of the erythrocyte production [11] and practically all the red cells are liberated from the bone marrow into the blood at the reticulocyte stage. Reticulocyte count is of great value in making differential diagnosis between anemias and also in estimating the effect of the treatment in various blood diseases.

Animal studies have shown that the rate of RBC production increases after the administration of thyroxin. Studies showed that thyroxin effect on RBC production is related to both calorigenic renal erythropoietin and non calorigenic T3 and T4. [4]

The effect of erythropoietin (EPO) on the formation of erythroid colonies is mediated by receptors with B2 adrenergic properties. Anemia observed in thyroidectomised animals conforms both mechanisms by being hypochromic and normocytic and associated with reticulocytopenia and hypoplasia of the erythropoietic tissue in the marrow. [4] In this study, most of the cases showed that normocytic and normochromic anaemia and in two cases reticulocyte count was increased with eltroxine therapy after two months of duration.

In adults also hypothyroidism was confirmed by both T3 and T4 levels. There was significant lower values compared to controls i.e. T3 0.33+0.25 nanogm/dl and T4, 0.72+1.20 mcg/dl. Simultaneously by TSH levels at least two to three times in the upper normal limit of 46.56+15.83 microunits/ml (normal levels: 0.3 – 6.5 microunits/ml) which was similar to paediatric cases.

The reticulocyte count in adults showed significant decrease compared to pediatric cases. The normocytic, normochromic type of anaemia was found as a frequent type in many of our cases.

Conclusion:

There was an increase in TSH levels which indicate the severity of hypothyroidism. The decrease in reticulocyte counts in hypothyroid cases showed the effect of thyroid hormones on erythropoiesis. Reticulocyte count can be used as an alternate economical and accessible indicator in knowing the prognosis of hypothyroidism as RIA of thyroid hormones is expensive and almost all hypothyroid cases need lifelong treatment and regular assessment.

 

References:

  1. Neel JV, Carr EA, Beierwaltes WH, Davidson RT. Genetic studies on the congenitally hypothyroid. Pediatrics 1961 Feb;27:269-85
  2. Raghupathy P. Endocrine system. In. SwarnaRekhaBhat editor. Achar’s textbook of Pediatrics. 4th Universities Press (India) Pvt. Ltd. 2009: 538
  3. Briggs C, Bain BJ. Basic Hematological Techniques. In. Bain BJ, Bates I, Laffan MA, Lewis SM, Editors. Dacie and Lewis Practical Hematology. 11th Elsevier 2012: 33-49
  4. Gregg XT, Prchan JT. Anemia of Endocrine Disorders. In. Kaushansky K, Lichtman MA, Beutler E, Kipps TJ, Seligsohn U, Prchal JT. Editors. Williams Hematology. 8th McGraw Hill 1991: 509-10
  5. Hillman RS. Characteristics of marrow production and reticulocyte maturation in normal man in response to anemia. J Clin Invest. 1969 Mar;48(3):443-53.
  6. Demers LM, Spencer C. The Thyroid: Pathophysiology and Thyroid Function Testing. In. Burtis CA, Ashwood ER, Bruns DE. Editors. TIETS Textbook of Clinical Chemistry and Molecular Diagnostics.4th Elsevier 2008: 2066-86
  7. Godkar PB, Godkar DP. Determination of Hemoglobin. In. Textbook of Medical Laboratory Technology. 2nd Bhalani Publishing House. 2011 Oct:727-30
  8. Godkar PB, Godkar DP. Determination of Reticulocyte count. In. Textbook of Medical Laboratory Technology. 2nd Bhalani Publishing House. 2011 Oct:750-51
  9. Roger A, Bauman. Technetium – 99m pertechnetate scans in congenital hypothyroidism. J Pediatr 1976 Aug;89:268
  10. Davenport J. Macrocytic anemia. Am Fam Physician 1996 Jan;53(1):155-62
  11. Seip M. Reticulocyte Studies. Acta Med Scandinav. 1953;Suppl 282:1-164

 

Acknowledgements:

I am thankful to Dr. K. Krishnaveni MD; MSc (Applied Nutrition), Professor of Physiology, Gandhi Medical College, Dr. Bhanumathi MD; Professor and Head, Department of Radiology and Dr. Anitha Sethi MD; Associate Professor of Pediatrics, Niloufer Hospital, Hyderabad for their kind help in completion of my project. I am also greatful to Dr. Prabhakar Shastri MD; Professor of Endocrinology, Gandhi Medical College for his guidance.

Source of support: Nil. Conflict of interest: Not Declared





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