Implementing a Screening Protocol for Endocrinopathies in Patients with Secondary Hemochromatosis Due to Sickle Cell Anemia

Objective:
Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy characterized by hemolytic anemia, intermittent small vessel occlusion, and organ dysfunction. Red blood cell transfusions are a therapeutic mainstay in SCD, which can lead to iron overload and endocrine disease. However, due to diagnostic difficulties and lack of data, there is not a wide consensus in approach. This has led to many practitioners screening for endocrinopathies only once patients are symptomatic. In this study, we implemented a standardized protocol for screening of iron overload and certain endocrinopathies in a single-study cohort of patients with SCD to assess viability in real-world practice and to detect disease prior to significant burden.

Methods:
We studied 19 patients diagnosed with SCD or sickle-cell trait (SCT) at a single institution. Patients had serum testing for ferritin and a metabolic panel at usual clinical visits. Iron overload was diagnosed with serum ferritin levels of at least 1000 ng/mL. If iron overload was detected, additional testing for 25-Hydroxyvitamin D (OHD), Thyroid Stimulating Hormone (TSH), Parathyroid Hormone (PTH), and Insulin-Like Growth Factor-1 (IGF-1) was obtained.

Results:
Nineteen patients (12 men and 7 women) were included with a mean age of 32 years old. Twelve patients and seven patients were diagnosed with SCD and SCT, respectively. The average ferritin levels of SCD and SCT patients were 4874 and 270 ng/mL, respectively. Nine patients had ferritin levels greater than 1000 ng/mL, eight of which were diagnosed with SCD, one was diagnosed with SCT, and seven of which were prescribed iron chelation therapy. Of these nine patients, the average random glucose was 103 ng/mL. The average serum calcium corrected for albumin levels was 9.3 ng/mL. Seven of eight patients were found to have low 25-OHD levels with two of four patients showing elevated serum PTH. One of six patients had abnormal thyroid testing, with an elevated TSH and normal free thyroxine. Three of five patients showed abnormal IGF-1 testing, with low IGF-1 levels and low IGF-1 binding protein levels.

Discussion/Conclusion:
This study successfully implemented a protocol for screening for endocrinopathies in a cohort of SCD and SCT patients at a single institution. We showed evidence that many patients with iron overload demonstrated abnormalities in 25-OHD, PTH, TSH, and IGF-1. The few studies that have been done to analyze this topic have shown findings of growth failure, osteopenia, hypogonadism, hypothyroidism, and glucose intolerance in SCD and SCT patients. This study did not explore bone disease or sex hormone function due to difficulty in performing these tests and obtaining insurance payor coverage. An additional limitation includes low sample size. However, this study replicates real-world care for these patients due to these barriers, making these methods easily translatable to other clinical settings. Our findings suggest implementation of a standardized protocol for iron overload and endocrinopathy screening in SCD and SCT patients is not only viable but could also detect disease before symptom onset when intervention is more effective.