What adjustments should be made to the medication regimen for a patient with hypothyroidism (underactive thyroid) and iron deficiency anemia, given their current lab results and medical history?

Medication Management for Hypothyroidism with Anemia

Continue thyroxine at the current regimen (1 tablet daily Mon-Fri, 2 tablets Sat-Sun) as the TSH is well-controlled at 2.3, and discontinue iron supplementation permanently given the normal ferritin of 368 and absence of true iron deficiency. 1

Thyroid Medication Assessment

The current thyroxine dosing should be maintained without adjustment. 1

• The TSH of 2.3 mU/L is within the normal range and indicates adequate thyroid hormone replacement 1
• For adults with hypothyroidism, the goal is to normalize TSH levels, which has been achieved in this patient 1
• The unconventional dosing schedule (1 tablet Mon-Fri, 2 tablets Sat-Sun) appears to be providing adequate control and should not be changed 1
• No dose adjustment is warranted when TSH is normalized and the patient is clinically euthyroid 1

Iron Supplementation Decision

Iron tablets should remain discontinued. 2

Iron Studies Interpretation:

• Ferritin 368 ng/mL is well above the threshold for iron deficiency (normal range, no deficiency) 2
• Iron 15 and transferrin saturation 0.27 are within normal limits 2
• These values indicate adequate iron stores and no indication for supplementation 2

Anemia Etiology:

The mild anemia (Hb 106 g/L) with normal MCV (97 fL) and elevated MCH (34) is not due to iron deficiency but rather represents the normocytic anemia commonly associated with hypothyroidism itself. 3

• Anemia occurs in approximately 20-30% of hypothyroid patients even with adequate iron stores 3
• The MCV in hypothyroidism averages around 90 fL, and macrocytosis can occur without B12 or folate deficiency 3
• This anemia typically improves with thyroid hormone replacement alone, without iron supplementation 3
• The hemoglobin has been relatively stable (100-113 g/L range over time), suggesting chronic stable anemia of hypothyroidism rather than progressive iron deficiency 3

Additional Hematologic Findings

The mild leukopenia (WCC 3.3) and neutropenia (1.6) warrant monitoring but not immediate intervention. 3

• These findings can be associated with hypothyroidism itself 3
• Serial monitoring every 3-6 months is appropriate to ensure stability 2
• If values continue to decline or the patient develops recurrent infections, further hematologic evaluation would be indicated 3

Monitoring Plan

Check TSH and complete blood count in 3 months: 1

• TSH should remain in the normal range (approximately 0.5-4.5 mU/L) 1
• Hemoglobin may gradually improve with continued adequate thyroid replacement 3
• If hemoglobin drops below 100 g/L or MCV becomes microcytic (<80 fL), reassess iron studies at that time 2

Key Clinical Pitfall to Avoid

Do not restart iron supplementation based solely on mild anemia when ferritin is normal. 2

• Iron supplementation is only indicated when ferritin is low (typically <15-30 ng/mL in the general population) 2
• Unnecessary iron supplementation can lead to iron overload, gastrointestinal side effects, and does not address the underlying cause of anemia in this case 2
• The anemia of hypothyroidism responds to thyroid hormone replacement, not iron 3