Can Prenessa cause blood count deterioration over time?

Yes, according to the Summary of Product Characteristics, deterioration of morphology - thrombocytopenia, leukopenia, agranulocytosis, aplastic anemia, anemia,
one of the very rare side effects of Prenessa.

If you have observed a decrease in haemoglobin levels and other changes in your blood count, I encourage you to consult your doctor. Your doctor will be able to carry out a comprehensive assessment of your health, including appropriate tests and analyses to identify possible causes of the drop in haemoglobin levels and other abnormalities in your blood count.

Please do not stop taking the medication on your own. Any modifications in therapy, including discontinuation of the drug, should be made after consultation with the attending physician who is familiar with your health condition in detail. You can read more about it here: https://www.gdziepolek.pl/artykuly/czy-jak-i-kiedy-mozna-odstawic-leki

I encourage you to report the symptoms you are experiencing to your doctor, as well as to report the occurrence of an adverse reaction of the preparation. Reporting side effects allows you to increase control over the medicines available on the market. We wrote more about how and why to report side effects in the article: https://www.gdziepolek.pl/artykuly/jak-i-dlaczego-zglaszac-dzialania-niepozadane