Frequent blood transfusionsare necessaryin sickle cell diseaseto manage chronic—often severe—anemia.Chronic transfusions canlead to iron overload,manifestations thatmay appear indirectlyas endocrine functiondisorders, such as hypothyroidism.Testing,however, can reveal theunderlying cause.
Initial Presentation
Nancy A. is an African-American woman 32 years of age, married, mother of two young daughters, and currentlyunemployed. She has SS genotype sickle cell disease (SCD). She presented to a sickle cell center for a follow-up visitwith complaints of extreme fatigue and intermittent pain in her back and shins that had persisted for the past 3 days.Her pain was reported as 5/10 on the linear pain scale (0 = no pain, 10 = excruciating pain).
Diagnosis and Treatment
Nancy was diagnosed with chronic anemia due to hemolysis of the sickled red cells. Intermittent blood transfusionsmight be required if her hemoglobin fell 2 g/dL below her baseline, which is 8 g/dL. A blood test yielded these results:hemoglobin 8.6 g/dL; hematocrit 24.9%; white blood count 12.2 mcg/L; reticulocyte count 9.4%;thyroid-stimulating hormone (TSH) 6.56 mIU/L; ferritin 3226.0 mcg/L (which was high); mean corpuscular volume106.2 fL; and fetal hemoglobin 15.7%.
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Nancy was scheduled for a thyroid ultrasound to check for thyroid nodules. Because of her high serum ferritin, shewas placed on daily chelation therapy with deferasirox 1500 mg daily (based on 20 mg/kg—the minimum approvedinitial dosage with the maximum efficacy and the fewest side effects). With deferasirox, the dosage can be increasedto 25 mg/kg to 30 mg/kg over time (3-6 months) if a patient shows no response to therapy; 40 mg/kg is the maximumapproved dosage.
Nancy underwent ophthalmic and auditory exams prior to starting deferasirox, as ocular and aural disturbanceshave been reported with deferasirox usage. She was taught how to adhere to the medication regimen. She wasadvised that deferasirox may cause stomach upset, nausea, and diarrhea, but that by increasing fiber in her diet, theseside effects may be lessened. She was educated on the importance of tracking her transfusions and units of red bloodcells transfused, and of adhering to monthly follow-up visits for laboratory tests to monitor her ferritin, kidney andliver functions, and complete blood count. She was given a personal medical record booklet to note her test resultsand advised to bring it with her to each doctor visit.
Follow-Up
Nancy received a thyroid ultrasound that revealed mild thyromegaly but no thyroid nodules. Her ophthalmic andauditory exams were normal. She continues with daily deferasirox therapy and has monthly tests to monitor herferritin and TSH levels. Her most recent ferritin level was 2644.0 mcg/L (normal range is 13.0 mcg/L-150 mcg/L); her TSH level was 4.90 mIU/L (normal TSH range is 0.27 mIU/L-4.2 mIU/L). As is typical with patients with SCD who havechronic transfusional iron overload, chelation therapy with deferasirox is initiated whenever Nancy’s ferritin levelsreach >1000 mcg/L; patients with ferritin levels of 500 mcg/L to 1000 mcg/L should be educated about iron overloadand monitored. With Nancy, this is an ongoing process.
Discussion
Iron overload affects such endocrine organs as the thyroid gland, pancreas, ovaries, testes, liver, and pituitary gland,as well as the heart and brain. Early signs of hypothyroidism, diabetes, and menstrual disorders may be related toiron overload in patients with SCD. Nurses should be alert for such signs and target patients who are at risk.
