Critical Comments

The subject of the Rhineland Study as described in the article is highly relevant (1).

We have critical comments regarding three points:

• The benchmark for undertreatment was a TSH concentration above 4.27 mU/L.

  • This is not consistent with the recommendations of the German College of General Practitioners and Family Physicians (DEGAM) guideline on this subject (2). The guideline provides that a TSH concentration in 70–80 years old is considered elevated at a level of >5 mU/L and in those older than 80 at a level of >6 mU/L.

  • Up to 10 mU/L, no substitution is recommended and in people older than 75 years, this is not needed in concentrations up to 20 mU/L.

Consequently there will be much less undertreatment.

• A TSH concentration between 0.56 mU/L and 4.27 mU/L is not confirmation of successful substitution. In many patients without a clear indication, the L-thyroxin dose can be tapered out under TSH monitoring.

• According to some statements, not enough TSH monitoring controls are carried out. In 2022, 22.5 million measurements were taken (personal communication from the Zentralinstitut für die kassenärztliche Versorgung [ZI, the central institute for statutory health insurance provision/care provision], dated 22 June 2023).

• Monitoring TSH concentrations is costly, at €3 for the laboratory expenditure. In older persons—except in acute decompensation and/or dose finding periods—much longer monitoring intervals are sufficient (every 5 years) (3).

Tracing overtreatment and undertreatment with thyroid hormone and putting a stop to it requires a high level of commitment. The article raises awareness of the subject, but it underestimates overtreatment and overestimates undertreatment.