Iron Overload and Endocrine Dysfunction in Adults with Transfusion-Dependent Beta-Thalassemia and Growth Retardation: A Correlational Study

Abstract

Background and Objective: Iron overload remains a significant clinical concern in patients with transfusion-dependent beta-thalassemia (TDT). This study aims to characterize the iron load and endocrine profile of adult transfusion-dependent beta-thalassemia patients and to evaluate their correlation with growth retardation. Methods: A cross-sectional study was conducted at PIMS Hospital, Islamabad, involving 62 adult patients with homozygous or HbE beta-thalassemia receiving regular blood transfusions. Iron overload was assessed using serum ferritin (SF) and transferrin saturation (TS), while endocrine function was evaluated through measurements of thyroid-stimulating hormone-sensitive (TSH), free thyroxine (FT4), and insulin-like growth factor-1 (IGF-1). Data was analyzed using SPSS v26.0 and R v4.3.1, which included Pearson correlation, chi-square testing, and multivariable regression to explore associations between iron indices and endocrine dysfunction. Results: Serum ferritin demonstrated significant negative correlations with FT4 (r = −0.348, p = 0.005) and IGF-1 (r = −0.302, p = 0.015). MRI T2* pancreas values correlated positively with FT4 (r = 0.268, p = 0.037) and IGF-1 (r = 0.312, p = 0.015). Patients with ferritin > 5000 ng/mL exhibited a higher prevalence of low IGF-1 levels (89.2% vs. 64.0%, p = 0.018). No significant gender-based differences were observed in endocrine parameters. Conclusion: Pancreatic iron burden and elevated serum ferritin were significantly associated with impaired thyroid and growth axis function, highlighting the value of integrating MRI T2* and biochemical markers for early endocrine risk stratification in adult TDT patients.

1. Introduction

Beta-thalassemia is a hereditary hemoglobin disorder characterized by reduced or absent beta-globin chain synthesis, resulting in chronic anemia and the need for lifelong transfusion therapy in transfusion-dependent thalassemia (TDT). Globally, approximately 1.5% of the population carries a beta-thalassemia mutation, and more than 60,000 affected infants are born annually [1]. Advances in transfusion safety, iron chelation therapy, and endocrine surveillance have significantly improved life expectancy in high-income countries; however, endocrine complications remain among the most frequent long-term morbidities [2,3]. International studies consistently report that 40–60% of adults with TDT develop endocrine dysfunction, including hypothyroidism, hypogonadism, impaired glucose regulation, and growth hormone-IGF-1 axis abnormalities [4,5]. These complications are largely attributed to transfusional iron overload, with excess iron accumulating in endocrine tissues and disrupting hormonal secretion.

The burden is considerably higher in low- and middle-income countries due to delayed diagnosis, inconsistent transfusion programs, and limited access to optimal chelation therapy. Studies have demonstrated that organ-specific iron deposition, particularly in the pancreas and pituitary gland, is strongly associated with endocrine dysfunction, with MRI T2* emerging as a reliable tool for quantifying tissue iron load [6,7,8]. Despite these advances, many resource-limited settings continue to rely on serum ferritin and transferrin saturation as practical surrogate markers, although their accuracy in predicting endocrine outcomes especially in adults varies across populations.

South Asia bears a disproportionate share of the thalassemia burden. India and Bangladesh report high rates of growth retardation and endocrine abnormalities among TDT patients, often linked to suboptimal chelation practices and persistent iron overload [9]. In Pakistan, where the carrier rate is estimated at 5–7%, multiple regional studies highlight the severity of endocrine morbidity. A study from Peshawar reported short stature in 52.7% of TDT patients, with elevated ferritin levels strongly associated with poor growth outcomes [10]. Another study found endocrine abnormalities in 73.9% of beta-thalassemia major patients, with serum ferritin showing a significant correlation with thyroid dysfunction and delayed puberty [11]. More recent evidence suggests that pancreatic iron deposition, as assessed by MRI T2*, may be particularly relevant for predicting disturbances in glucose metabolism and IGF-1 levels, although access to advanced imaging remains limited [12,13].

Despite substantial research involving children and adolescents, adult TDT patients, especially those with persistent growth retardation, remain understudied, even though survival into adulthood is increasingly common. This gap is critical because adults with longstanding iron overload often exhibit more advanced endocrine sequelae that significantly affect metabolic health, fertility, bone density, and overall quality of life. Furthermore, the predictive accuracy of serum ferritin, transferrin saturation, and pancreatic MRI T2* for endocrine risk in this adult subgroup has not been adequately evaluated in Pakistan. Therefore, the present study aims to address this gap by assessing the correlation between iron overload measured through serum ferritin, transferrin saturation, and MRI T2* of the pancreas and endocrine function, specifically thyroid hormones and IGF-1 levels, in adults with transfusion-dependent beta-thalassemia and documented growth retardation.

2. Materials and Methods

2.1. Study Design and Sample Size

This cross-sectional study evaluated the association between iron overload and endocrine function among adult patients with transfusion-dependent beta-thalassemia (TDT) with documented growth retardation. This study was conducted at the Department of Oncology, Pakistan Institute of Medical Sciences (PIMS), Islamabad, from January 2024 to January 2025. Sample size of 62 calculated using an expected correlation coefficient (r) of 0.35, level of significance level (α) of 0.05 and statistical power (1 − β) at 80% to ensure adequate sensitivity for detecting a true effect using MedCalc’s version 14.12.0 sample size calculator [14] and by guidelines from Bujang and Baharum, who recommended a minimum of 50–85 subjects for moderate correlations in clinical settings [15].

2.2. Study Population and Eligibility Criteria

Participants were selected using a purposive sampling technique from the PIMS thalassemia outpatient clinic. Eligible individuals were adults aged 18 years or older with a confirmed diagnosis of homozygous β-thalassemia major or β-thalassemia/HbE disease, verified through high-performance liquid chromatography (HPLC) or microcapillary electrophoresis. Only those classified as having growth retardation were included, defined by a height-for-age Z-score below −2 SD according to the WHO Growth Reference for individuals aged 5–19 years. For adults, short stature was interpreted as a lifelong height deficit resulting from childhood undergrowth [16]. Participants were excluded if they had positive HBsAg or anti-HCV serology, known primary thyroid disorders, pituitary disease, or growth hormone deficiency not attributed to iron overload. Pregnant individuals and those unwilling to provide written informed consent were also excluded.

2.3. Ethical Considerations

Study protocol was reviewed and approved by the Ethical Committee of the Lady Reading Hospital (Ref no: 448/LRH/MTI). All participants provided written informed consent prior to enrollment, and this study was conducted in accordance with the principles outlined in the Declaration of Helsinki.

2.4. Sample Collection and Laboratory Analysis

Venous blood samples were collected immediately prior to each participant’s scheduled transfusion, with two tubes (7 mL and 3 mL) drawn for hematological and biochemical analyses. All investigations were conducted at the Clinical Pathology Laboratory, PIMS. Iron Overload Assessment: Serum iron (SI) and total iron-binding capacity (TIBC) were measured using a direct colorimetric method on the Roche COBAS^® Integra 400 Plus (Roche Diagnostics, Mannheim, Germany) or COBAS^® 6000 (Roche Diagnostics, Mannheim, Germany) clinical chemistry analyzer. Transferrin saturation (TS) was calculated from SI and TIBC using the formula: TS (%) = 100 × [Serum Iron (µg/dL)/TIBC (µg/dL)]. All serum iron and TIBC measurements were obtained from fasting, pre-transfusion, non-hemolyzed morning samples to ensure accuracy of TS calculation. TS values were recalculated manually from raw SI and TIBC data, and any physiologically implausible values (>100%) were rechecked and corrected after verification against original laboratory reports. Serum ferritin (SF) was quantified using a chemiluminescent immunoassay (CLIA/CMIA) performed on the Beckman Coulter Access 2 (Beckman Coulter, Inc., Brea, CA, USA) or DxI 800 analyzer (Beckman Coulter, Inc., Brea, CA, USA). Endocrine Assessment: Thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were measured using electrochemiluminescence immunoassay (ECLIA) on the Roche Elecsys^® e411/e601/e602 platform (Roche Diagnostics, Mannheim, Germany). Insulin-like Growth Factor-1 (IGF-1) was measured using a solid-phase ECLIA method on the Lifotronic eCL8000 analyzer (Shenzhen Lifotronic Technology Co., Ltd., Shenzhen, China), with values interpreted according to age- and sex-specific reference ranges provided by the manufacturer. Pancreatic Iron (MRI T2*): When available, pancreatic iron measurements were obtained from MRI T2* studies performed on a 1.5-Tesla system using standardized multi-echo gradient-echo sequences. Pancreatic iron burden was expressed as T2* relaxation times (ms), with lower T2* values indicating higher iron deposition.

2.5. Statistical Analysis

Statistical analysis was conducted using SPSS version 26.0 and R version 4.3.1. Continuous variables were assessed for normality using the Shapiro–Wilk test and were presented as mean ± standard deviation (SD) or median with interquartile range (IQR), depending on the data distribution. Categorical variables were summarized as frequencies and percentages. Comparisons between groups were performed using the independent t-test or Mann–Whitney U test for continuous variables and the chi-square test or Fisher’s exact test for categorical variables. Associations between biochemical markers, including serum ferritin (SF), transferrin saturation (TS), MRI T2*, thyroid-stimulating hormone (TSH), free thyroxine (FT4), and insulin-like growth factor-1 (IGF-1), were analyzed using Pearson correlation for normally distributed variables and Spearman correlation for non-normally distributed variables. Correlation analyses were limited to the performed comparisons, with no logistic regression or partial correlation models applied. All statistical tests were two-tailed, and a p-value of less than 0.05 was considered statistically significant.

3. Results

3.1. Baseline Characteristics

A total of 62 adult patients with transfusion-dependent beta-thalassemia (TDT) and documented growth retardation were enrolled. There were 34 males (54.8%) and 28 females (45.2%). The majority had homozygous beta-thalassemia (n = 60, 96.8%), while two patients (3.2%) had HbE beta-thalassemia. The median age was 22 years (range 18–26). Pre-transfusion hemoglobin levels averaged 8.5 ± 1.2 g/dL, indicating moderate anemia. Anthropometric assessment revealed a median weight of 42.0 kg (28–55 kg), median BMI of 18.2 kg/m² (14.8–22.5), and mean height of 148.2 ± 7.9 cm. The mean mid-parental height was 161.8 ± 8.5 cm, suggesting significant deviation from expected growth potential. Iron overload was substantial, with median serum ferritin (SF) of 5850 ng/mL (600–20,800) and median transferrin saturation (TS) of 92% (range 50–100). Values above 100% were excluded as physiologically implausible after verification of assay and timing relative to transfusion. Endocrine parameters showed a median TSH of 3.42 mU/L (0.65–8.1), median FT4 of 1.09 ng/dL (0.75–1.92), and median IGF-1 of 58 ng/mL (20–198). IGF-1 values were interpreted according to age- and sex-specific reference ranges from the manufacturer, and values below the lower limit of normal were classified as “low.” MRI T2* pancreas values were available for 42 participants (67.7%). MRI acquisition was performed on a 1.5-Tesla system (GE Healthcare) using multi-echo gradient-echo sequences with 8–12 echo times, slice thickness 8 mm, flip angle 20°, and breath-hold acquisition. ROI was placed on the pancreatic head/body, avoiding vessels and ducts. Patients with and without MRI T2* did not differ significantly in age, sex, SF, TS, or endocrine parameters as mentioned in

Table 1. Baseline characteristics of study participants (n = 62).

Variables.	n (%)/Median (Min–Max)/Mean (SD)
Gender, n (%)
Male	34 (54.8)
Female	28 (45.2)
Diagnosis, n (%)
Homozygous Beta Thalassemia	60 (96.8)
HbE Beta Thalassemia	2 (3.2)
Age (years), median (min–max)	22 (18–26)
Pre-transfusion hemoglobin (g/dL), mean (SD)	8.5 (1.2)
Weight (kg), median (min–max)	42.0 (28–55)
BMI (kg/m2), median (min–max)	18.2 (14.8–22.5)
Height (cm), mean (SD)	148.2 (7.9)
Mid-Parental Height (cm), mean (SD)	161.8 (8.5)
Serum ferritin (ng/mL), median (min–max)	5850 (600–20,800)
Transferrin saturation (%), median (min–max)	92 (15–106)
TSHs (mU/L), median (min–max)	3.42 (0.65–8.1)
FT4 (ng/dL), median (min–max)	1.09 (0.75–1.92)
IGF-1 (ng/mL), median (min–max)	58.0 (20–198)
MRI T2* Pancreas (ms) [n = 42], median (min–max)	12.9 (4.2–54.8)

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3.2. Endocrine Function

A total of 41 patients (66.1%) were euthyroid, and 19 (30.6%) had subclinical hypothyroidism (elevated TSH, normal FT4), and 2 (3.2%) had overt hypothyroidism. Using age- and sex-specific IGF-1 reference ranges, 49 patients (79.0%) had low IGF-1 levels, consistent with impaired growth hormone axis function, while 13 patients (21.0%) had normal levels as shown in

Table 2. Endocrine function of participants (n = 62).

Variables	n (%)
Thyroid function
Euthyroid (normal)	41 (66.1)
Hypothyroidism	2 (3.2)
Subclinical hypothyroidism	19 (30.6)
IGF-1
Normal	13 (21.0)
Low	49 (79.0)

.

3.3. Correlations Between Iron Overload and Endocrine Parameters

Transferrin saturation (TS) showed no significant correlations with TSH (r = 0.012, p = 0.922), FT4 (r = 0.025, p = 0.845), or IGF-1 (r = −0.158, p = 0.224) as mentioned in

Table 3. Correlation of transferrin saturation with endocrine parameters (n = 62).

Variables	r	p-Value
TS-TSH	0.012	0.922
TS-FT4	0.025	0.845
TS-IGF-1	−0.158	0.224

.

Serum ferritin (SF) showed no correlation with TSH (r = 0.082, p = 0.516) but a significant weak negative correlation with FT4 (r = −0.348, p = 0.005) and IGF-1 (r = −0.302, p = 0.015), indicating that higher iron burden was associated with lower thyroid hormone and IGF-1 levels as describe in mentioned in

Table 4. Correlation of serum ferritin with endocrine parameters (n = 62).

Variables	r	p-Value
SF-TSH	0.082	0.516
SF-FT4	−0.348	0.005 *
SF-IGF-1	−0.302	0.015 *

* p < 0.05 indicates statistical significance.

.

3.4. Sex-Based Comparisons

Median SF was slightly higher in males, 6050 ng/mL (IQR: 4800–8200), than in females, 5650 ng/mL (IQR: 4200–7900), p = 0.462. TS, TSH, FT4, and IGF-1 did not differ significantly between sexes as shown in

Table 5. Comparison of endocrine parameters between male and female patients (n = 62).

Variables	Male (n = 34) Median (IQR)/Mean (SD)	Female (n = 28) Median (IQR)/Mean (SD)	p-Value
SF (ng/mL)	6050 (4800–8200)	5650 (4200–7900)	0.462
TS (%)	94 (82–105)	91 (80–103)	0.513
TSH (mU/L)	3.38 (2.40–4.92)	3.47 (2.35–5.02)	0.782
FT4 (ng/dL)	1.08 (0.90–1.25)	1.10 (0.88–1.26)	0.744
IGF-1 (ng/mL)	56.5 (40–78)	59.0 (42–82)	0.638

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3.5. Association Between Ferritin and Endocrine Dysfunction

Patients with SF > 5000 ng/mL were more likely to have low IGF-1 (89.2% vs. 64.0%, p = 0.018), while overt hypothyroidism and subclinical hypothyroidism showed no significant associations (p = 0.505 and p = 0.367, respectively) as shown in

Table 6. Association between serum ferritin levels and endocrine dysfunction.

Endocrine Dysfunction	Ferritin ≤ 5000 ng/mL (n = 25), n (%)	Ferritin > 5000 ng/mL (n = 37), n (%)	p-Value
Low IGF-1	16 (64.0)	33 (89.2)	0.018 *
Overt hypothyroidism	0 (0.0)	2 (5.4)	0.505
Subclinical hypothyroidism	6 (24.0)	13 (35.1)	0.367

* p < 0.05 indicates statistical significance.

.

3.6. MRI T2* Pancreas and Endocrine Associations

Among the 42 patients with MRI T2*, there was no significant correlation with TSH (r = −0.082, p = 0.518). There were weak positive correlations with FT4 (r = 0.268, p = 0.037) and IGF-1 (r = 0.312, p = 0.015), indicating an association between lower pancreatic iron burden and better preservation of thyroid and growth hormone function as shown in

Table 7. Correlation between MRI T2* pancreas values and endocrine parameters.

Variables	r	p-Value
MRI T2* Pancreas-TSH	−0.082	0.518
MRI T2* Pancreas-FT4	0.268	0.037 *
MRI T2* Pancreas-IGF-1	0.312	0.015 *

* p < 0.05 indicates statistical significance.

.

4. Discussion

This study evaluated the endocrine profile of adult patients with transfusion-dependent beta-thalassemia (TDT) presenting with growth retardation, focusing on iron overload, gender-based differences, and pancreatic iron deposition assessed via MRI T2* imaging. This lifelong short stature in adult TDT patients reflects persistent growth deficits originating in childhood, highlighting how early pediatric growth impairment contributes to the short stature observed in adulthood. No significant gender differences were observed in endocrine parameters. However, elevated serum ferritin levels (>5000 ng/mL) were significantly associated with low IGF-1 levels, suggesting a relationship between systemic iron burden and impaired growth factor production. Moreover, MRI T2* pancreas values showed modest positive correlations with both FT4 and IGF-1, indicating that pancreatic iron deposition may be associated with thyroid and growth axis function.

Our findings are consistent with the prior literature highlighting the role of iron overload in endocrine dysfunction among beta-thalassemia patients. Several studies have demonstrated that elevated ferritin is predictive of growth hormone axis impairment and thyroid abnormalities. For example, Atmakusuma et al. reported a significant correlation between iron overload and reduced IGF-1 levels in adult thalassemia patients with growth retardation [17]. Similarly, Sevimli et al. (2022) found pancreatic iron deposition to be significantly associated with endocrine complications, including hypothyroidism and short stature [18]. Our results corroborate these observations, particularly the association between low MRI T2* pancreas values and reduced IGF-1, underscoring the pancreas as a sensitive site for iron-induced endocrine disruption.

The lack of significant sex-based differences in endocrine parameters aligns with Chung et al., who found no gender variation in ferritin-related endocrine complications [19]. Nevertheless, the strong association between high ferritin (>5000 ng/mL) and low IGF-1 highlights the importance of stratified endocrine surveillance based on iron burden rather than demographic factors. Thyroid dysfunction, although prevalent in thalassemia, showed weaker associations with ferritin, consistent with observations by Carsote et al. and Atmakusuma et al., who noted variable thyroid hormone responses to iron overload [11,17]. The modest correlation between pancreatic MRI T2* and FT4 (r = 0.268, p = 0.037) may reflect subclinical thyroid involvement, possibly influenced by systemic iron toxicity or pancreatic endocrine stress.

Emerging evidence supports MRI T2* of the pancreas as a non-invasive biomarker for endocrine risk stratification. Meloni et al. demonstrated that pancreatic T2* values predict disturbances in glucose metabolism and correlate with cardiac iron burden [12]. Our findings extend this application to thyroid and growth hormone axes, supporting the integration of MRI-based iron quantification with biochemical markers to improve early detection of endocrine complications, particularly in resource-limited settings where such complications may go underdiagnosed [20]. However, given that MRI T2* is not universally accessible in many low-resource healthcare settings, we have proposed an alternative monitoring panel that can be implemented without reliance on advanced imaging. This panel includes periodic measurement of serum ferritin (every 3 months), transferrin saturation (every 3–6 months), liver function tests, and a comprehensive endocrine profile comprising TSH, FT4, fasting glucose, IGF-1, and gonadal hormones, along with routine clinical assessment of growth patterns and pubertal development. Incorporating these measures ensures that our recommendations remain practical and clinically applicable in settings where MRI T2* cannot be routinely performed, and this approach is well supported by the existing literature [21].

This study has some important limitations. This cross-sectional design precludes causal inference; our findings demonstrate associations between iron overload and endocrine dysfunction but cannot establish direct causality. With that, this study was conducted at a single tertiary care center (PIMS, Islamabad), which may limit the generalizability of results to other populations or settings. Moreover, the relatively small sample size may reduce statistical power for detecting subtle associations, and MRI T2* was available for only a subset of participants. Longitudinal studies are needed to assess the progression of endocrine dysfunction over time, evaluate the effects of iron chelation on MRI T2* and hormonal recovery, and establish thresholds for intervention. Incorporating multi-organ MRI assessments and dynamic endocrine testing could further refine risk stratification and guide management strategies. Expanding research across diverse populations will improve generalizability and help optimize endocrine care in patients with beta-thalassemia.

5. Conclusions

Elevated serum ferritin in adult transfusion-dependent beta-thalassemia patients with growth retardation was significantly associated with low IGF-1, indicating impaired growth axis function. Pancreatic MRI T2* values correlated with FT4 and IGF-1, suggesting pancreatic iron burden as a potential marker of endocrine compromise. These findings support integrating biochemical and imaging assessments for early detection. Therapeutic interventions for identified endocrine disturbances include intensified iron chelation therapy, hormone replacement (thyroxine, sex steroids, or growth hormone where indicated), optimization of transfusion regimens, and multidisciplinary follow-up involving endocrinology and hematology. However, as a cross-sectional, single-center study, results demonstrate associations rather than causality and may have limited generalizability. Longitudinal studies are needed to validate these findings and guide clinical interventions.