pattern of blood cell parameters in thyroid dysfunction

INTRODUCTION

The biggest endocrine gland in the body is the thyroid gland. It produces and secretes 3, 5, 3'-triiodothyronine (T3) and 3, 5, 3', 5'-tetraiodothyronine (T4), also known as thyroxin. The anterior pituitary secretes thyroid-stimulating hormone (TSH) or thyrotropin, which regulates thyroid hormone function. Thyroid hormones are required for nearly all tissues' particularly for growth, differentiation, metabolic balance, and physiological function. Thyroid dysfunction is one of the most common endocrinal disorders.¹

Hyperthyroidism, hypothyroidism, and thyroid nodules are the most common thyroid disorders. Thyroid nodules are benign but can turn into malignancy. ²

Hypothyroidism is a clinical illness characterized by a reduction in thyroid hormone levels in the blood due to the hypo-functioning thyroid gland. ³

Thyrotoxicosis is a medical disorder resulting from high levels of thyroid hormone that affects tissues of

the human body. Increased hormone production and secretion from the thyroid gland causes hyperthyroidism, a kind of thyrotoxicosis. Graves' disease (GD) and toxic nodular goiter are the two most common causes of hyperthyroidism. ⁴

Thyroid hormone receptors are found on bone marrow cells, and thyroid hormone levels in the blood can influence blood cell development. ⁵

PATIENTS AND METHODS

This Prospective study was done from October 2020 to May 2021 at the clinical pathology department, Al-Azhar University Hospitals, Cairo, Egypt. The study included one hundred Egyptian patients suffering from thyroid dysfunction (hypothyroid and hyperthyroid patients) and fifty healthy volunteers (subjects without thyroid dysfunction) as a control group.

Inclusion criteria: Adult patients (>18 years) suffering from thyroid dysfunction (hyperthyroidism and hypothyroidism).

Exclusion criteria: Patients with chronic liver disease, chronic kidney disease, hematological diseases, autoimmune diseases, any diseases or drug intakes that could affect blood cell parameters, pregnancy, history of iron or vitamin supplementation in the previous 6 months, and acute illness history within at least 3 months prior to recruitment

Samples and Methods:

All patients underwent to the following a thorough history was taken, including any previous comorbid conditions such as diabetes, heart disease, or renal dysfunction.

Full Clinical Examination includes assessment of the general condition and vital signs. Abdominal, chest, and heart examinations were assessed with a focus on manifestations of the thyroid.

Blood sampling; two blood samples were collected from patients. 0.5 ml of venous blood on EDTA tubes for CBC and 2.5 ml of venous blood on a plain tube for thyroid hormonal assay.

The tubes containing EDTA were processed on a Sysmex XN-330 with five-parameter differential (Sysmex, Lincolnshire, IL, USA) for the determination of HCT (percent), Hb (g/dl), MCV (fl/cell), MCH (pg/cell), MCHC (g/dl), RDW (%), RDW (%), and platelet (PLT). White blood cell differential was assessed using fluorescence flow cytometry.

The plain tube was then centrifuged for 20 min at 3000 rpm. Serum was obtained and stored frozen until use at − 20°C. Using electro‑chemiluminescence immunoassay (ECLIA) on Cobas e411 (Roche Diagnostics International Ltd, Basel, Switzerland), free FT3, free FT4, and TSH quantitative measurements were done according to the manufacturer protocol.

Statistical analysis:

Statistical Program for Social Science (SPSS) version 18.0 from IBM was used in the analysis of data. Mean ± standard deviation (SD) was used to illustrate quantitative variables. Qualitative data were expressed as frequency and percentage. To equate proportions between two qualitative variables, the Chi-square (X2) test of significance was used.

RESULTS

As regard description of demographic data, the mean age of hypothyroid group was 44.1 ± 10.3 years, 13 were males (26%). Regarding haematological parameters,   results showed that the mean ±SD of RBCs, HCT, Hb, MCV, MCH, MCHC, RDW, PLTs were 4.4 ±0.7x106/ul, 36.1±6.3 %, 11.2 ± 2.0 g/dl, 68.2 ± 9.5 fl/cell, 26 ±3.2 pg/cell,  32.4±4.1 g/dl, 14.5±1.8 %, 282.8 ±83.8x106/ul, respectively. The mean of total WBC, neutrophils, lymphocytes, monocytes, and eosinophils were 7.1 x103/ul, 4.3 x103/ul, 2.5 x103/ul, 0.4 x103/ul, and 0.2 x103/ul, respectively. Among euthyroid group, the mean age was 44.6 ± 7.1 years, 16 were males (32%). Regarding haematological parameters, results showed that the mean of RBCs, HCT, Hb, MCV, MCH, MCHC, RDW, PLTs were 4.5 x106/ul, 39.5%,  12.4 g/dl, 81.7 fl/cell, 28.5 pg/cell, 34 g/dl, 13.4%, 274.4 x106/ul, respectively. The mean of total WBC count, neutrophils, lymphocytes, monocytes, and eosinophils were 7.1 x103/ul, 4.1 x103/ul, 2.6 x103/ul, 0.4 x103/ul, and 0.2 x103/ul, respectively.

The current study showed the prevalence of microcytic hypochromic anemia and anisocytosis in some patients. Anemia was significantly increased among hypothyroid patients in comparison with euthyroid subjects (50% in hypothyroid patients and 24% in euthyroid subjects; p-value < 0.05). The only type of anemia was microcytic hypochromic anemia.

As regard to patients with hyperthyroidism. The mean age was 44.6 ± 7.1 years, 16 were males (32%). Regarding haematological parameters, results showed that the mean ±SD of RBCs, HCT, Hb, MCV, MCH, MCHC, RDW, PLTs were 4.7 ±0.8x106/ul, 37.4 ±5.6%,  11.3±1.9 g/dl, 80.7 ±6.2 fl/cell, 27.6 ±2.7pg/cell, 32.8 ±3.9 g/dl, 14.2 ±1.9%, 283.2 ±94.0 x106/ul, respectively. The mean of total WBC, neutrophils, lymphocytes, monocytes, and eosinophils were 7.9 x103/ul, 4.8 x103/ul, 2.3 x103/ul, 0.5 x103/ul, and 0.2 x103/ul, respectively.

Results of the current study showed that the prevalence of anemia was significantly increased among hyperthyroid patients in comparison with euthyroid subjects (42% in hyperthyroid patients and 24% in euthyroid subjects; p-value < 0.05). Microcytic hypochromic anemia was the most frequent type of anemia (78.4%), followed by normocytic normochromic anemia (28.6%).

In table 1, no statistically significant difference was reported between the studied groups regarding sex and age (P-value > 0.05).

As shown in table 2, no statistically significant difference was noted between the studied groups regarding TLC, neutrophil, lymphocytes, monocytes, eosinophil, and basophil (P-value > 0.05).

Reticulocyte count showed a non-significant difference between the studied groups, as shown in table 3. P-value = 0.477.

As shown in table 4, a statistically significant association was reported between RDW and thyroid status (P-value = 0.001).

HCT and Hb were significantly lower in the hypothyroidism and hyperthyroidism groups than in the normal group (p-value < 0.05). In contrast, they were higher in the hyperthyroid group compared to the hypothyroid group (p-value < 0.05).

RDW was significantly higher in hyperthyroidism and hypothyroidism groups than in the normal group (p-value < 0.05). Also, it was significantly higher in the hyperthyroid group than the hypothyroid group (p-value < 0.05).

Hb, MCV and MCH were significantly lower in the hypothyroidism and hyperthyroidism groups than the normal group (p-value < 0.001).

No significant differences were reported between the study groups regarding RBCs, MCHC, and platelets (P-values > 0.05)

Table 1: Correlations between studied groups as regards demographic data.

Table  2 : comparisons between studied groups as regard WBCs count.

Table 3: comparisons between studied groups as regard reticulocyte count  (RC).

Table 4: comparisons between studied groups as regard RDW.

Table  5 : comparisons between studied groups as regard RBCs, indices & PLTs.