Can High TSH Occur Without a Thyroid Gland?
No, you cannot have an elevated TSH of 6.45 if you truly have no thyroid gland—this finding indicates you either still have thyroid tissue present or are not taking adequate thyroid hormone replacement. 1
Understanding the Physiology
Your situation requires immediate clarification of what "without thyroid" actually means:
If you had thyroidectomy or radioactive iodine ablation: You should be on levothyroxine replacement therapy. A TSH of 6.45 indicates your replacement dose is inadequate. 2, 3
If you have no thyroid tissue at all and are not on replacement: TSH would be extremely elevated (typically >50-100 mIU/L), not 6.45. Your level suggests residual thyroid function or partial replacement. 4
Your Symptoms Explained
Your anxiety, stress, and decreased appetite are likely caused by inadequate thyroid hormone replacement (hypothyroidism), not hyperthyroidism. 2
The connection works as follows:
Hypothyroidism causes: Fatigue, depression, anxiety, weight changes, constipation, cold intolerance, and cognitive slowing. 4, 3
TSH >4.5-5.0 mIU/L with symptoms: This represents overt or symptomatic hypothyroidism requiring treatment adjustment. 1, 3
Anxiety and thyroid dysfunction: There is significant bidirectional relationship—thyroid disorders commonly present with anxiety symptoms, and anxiety can be associated with subtle thyroid dysfunction. 1
Immediate Action Required
You need your free T4 (FT4) level checked immediately along with the TSH to determine if you have overt hypothyroidism. 1, 3
If FT4 is low: You have overt hypothyroidism and need levothyroxine dose increase. 2, 3
If FT4 is normal: You have subclinical hypothyroidism, but with your symptoms, treatment is still warranted. 3
Treatment Approach
For TSH 6.45 with symptoms in a patient on thyroid replacement, increase levothyroxine dose and recheck TSH/FT4 in 6-12 weeks. 2, 3
Specific considerations:
Typical dose adjustment: Increase by 12.5-25 mcg daily increments. 2
Target TSH: Aim for 0.4-2.5 mIU/L (lower half of reference range) for symptom resolution. 3
Timing matters: Take levothyroxine on empty stomach, 30-60 minutes before food. 2
Common Pitfalls to Avoid
Do not assume your anxiety is purely psychological—inadequate thyroid replacement directly causes neuropsychiatric symptoms including anxiety. 1
Critical errors to avoid:
Taking medications that interfere with absorption: Iron, calcium supplements, proton pump inhibitors reduce levothyroxine absorption—separate by 4 hours. 2
Inconsistent medication timing: Variable absorption leads to fluctuating thyroid levels. 2
Not rechecking after dose changes: Wait full 6-12 weeks before adjusting again due to levothyroxine's long half-life. 2, 3
Attributing all symptoms to stress/anxiety: Your elevated TSH proves inadequate thyroid hormone is contributing to your symptoms. 1
Verify Your Diagnosis
Confirm with your physician whether you actually have NO thyroid tissue versus partial thyroid function remaining. 1
This distinction is critical because:
Complete absence: Requires lifelong replacement with higher doses (typically 1.5-1.7 mcg/kg/day). 2
Partial function: May need lower replacement doses but still requires optimization. 3
Your decreased appetite with stress could be multifactorial, but the elevated TSH definitively indicates inadequate thyroid hormone, which itself causes metabolic slowing and can contribute to appetite changes. 2, 4