What evaluation and treatment should be pursued for a 64‑year‑old patient presenting with fatigue, brain fog, diffuse hair loss, and brittle nails?

Evaluation and Management of a 64-Year-Old with Fatigue, Brain Fog, Hair Loss, and Brittle Nails

This symptom constellation strongly suggests hypothyroidism and/or iron deficiency, and you should immediately order a complete blood count (CBC), serum ferritin, thyroid-stimulating hormone (TSH), and free T4 to identify these highly treatable causes. 1

Initial Laboratory Evaluation

Order these tests first:

• Complete blood count (CBC) to assess for anemia 1
• Serum ferritin to evaluate iron stores (target >100 ng/mL for optimal hair and nail health) 1, 2
• TSH and free T4 to screen for thyroid dysfunction 1, 3
• Vitamin B12 and folate levels, particularly if macrocytic anemia is present 4, 1
• Vitamin D level, as deficiency is linked to muscle fatigue 1
• Comprehensive metabolic panel including electrolytes (sodium, potassium, calcium, magnesium) 1

The rationale for this approach is that these specific symptoms—fatigue, cognitive impairment ("brain fog"), diffuse hair loss, and brittle nails—are classic manifestations of both hypothyroidism and iron deficiency, conditions that are extremely common in this age group and highly responsive to treatment 2, 5, 6, 7.

Interpreting Results and Treatment Decisions

If Hypothyroidism is Confirmed (Elevated TSH, Low Free T4):

Start levothyroxine 1.6 mcg/kg/day orally once daily, taken on an empty stomach 30-60 minutes before breakfast. 3

• Recheck TSH and free T4 in 6-8 weeks after starting treatment 3
• Continue monitoring every 6-8 weeks after any dose adjustment until TSH normalizes 3
• Once stable, monitor TSH every 6-12 months 3
• Important caveat: Brain fog symptoms in hypothyroidism often predate diagnosis and may persist despite normalization of thyroid function tests in some patients, requiring additional cognitive rehabilitation strategies 5, 6

If Iron Deficiency is Confirmed (Low Ferritin, with or without Anemia):

For a 64-year-old, you must identify the source of iron loss before treating. 2

• In postmenopausal women and men, gastrointestinal blood loss is the most common cause and requires evaluation for colon cancer and other GI pathology 2
• Order fecal occult blood testing and refer for colonoscopy if not recently completed 2
• Screen for malabsorption disorders 2

Once bleeding sources are excluded or addressed, start oral iron supplementation:

• Ferrous sulfate 325 mg (65 mg elemental iron) once to three times daily 2
• Recheck hemoglobin and ferritin at 13 weeks after initiating therapy 1
• Critical warning: Avoid excessive iron supplementation, which can cause iron overload, especially in patients with hereditary hemochromatosis 2

Regarding hair loss and brittle nails: While the relationship between iron deficiency and hair loss remains somewhat controversial in the literature, iron deficiency is associated with structural changes in hair and nails, and treating iron deficiency (even without frank anemia) often improves these symptoms 2, 7.

Additional Systematic Assessment

If initial tests are normal or symptoms persist despite treatment, expand evaluation:

• Depression screening using a validated tool, as depression commonly co-occurs with fatigue and cognitive symptoms 4
• Sleep assessment for obstructive sleep apnea and sleep quality 1
• Medication review for polypharmacy and drug interactions that contribute to fatigue 4, 1
• Nutritional assessment for deficiencies in copper, zinc, phosphate, and magnesium 1

Monitoring Fatigue Severity

Use a 0-10 numeric rating scale at each visit to quantify fatigue intensity: 1

• 0-3: Mild fatigue
• 4-6: Moderate fatigue
• 7-10: Severe fatigue

This standardized approach guides treatment intensity and helps track response to interventions 1.

Non-Pharmacologic Interventions

If fatigue persists despite correcting identified deficiencies, implement these evidence-based strategies:

• Moderate-intensity exercise (walking, swimming, cycling) for 30-60 minutes, 2-3 times weekly, starting with low-level activities if significantly deconditioned 4, 1
• Cognitive behavioral therapy (CBT) or mindfulness-based programs, which have demonstrated benefit for persistent fatigue 4
• Sleep hygiene education: maintain regular sleep schedule, create dark/quiet sleep environment 1
• Energy conservation strategies to maintain function 4

When to Refer

Refer to specialists if: 1

• Fatigue persists despite treatment of identified causes
• New symptoms or findings appear
• Substantial nutritional abnormalities require dietitian consultation
• Cognitive symptoms warrant neuropsychological evaluation

Establish collaborative care between primary care and specialists for ongoing surveillance. 8, 1

Common Pitfalls to Avoid

• Do not assume normal thyroid function tests exclude thyroid-related brain fog—some patients experience persistent cognitive symptoms despite biochemical euthyroidism and may benefit from cognitive rehabilitation 5, 6
• Do not treat iron deficiency in postmenopausal women or men without investigating for GI blood loss—this could delay diagnosis of colon cancer 2
• Do not overlook medication review—polypharmacy is an easily modifiable cause of fatigue in older adults 4, 1
• Do not fail to reassess after treatment initiation—regular follow-up ensures treatment effectiveness and identifies persistent symptoms requiring additional intervention 8, 1