title: Characterization of recombinant human and bovine thyroid-stimulating hormone preparations by mass spectrometry and determination of their endotoxin content.
abstract: BACKGROUND
  The TSH stimulation test to confirm canine hypothyroidism is commonly performed using a recombinant human TSH (rhTSH), as up to date, canine TSH is not yet commercially available. Limiting factors for the use of rhTSH are its high costs and occasional difficulties in product availability. Less expensive bovine TSH preparations (bTSH) purified from bovine pituitary glands are readily commercially available. The aim of this study was to evaluate two different bTSH products as alternative to rhTSH using mass spectrometry.
  
  
  RESULTS
  More than 50 proteins, including other pituitary hormones, bovine albumin, hemoglobin, and tissue proteins were identified in the bTSH preparations. In contrast, rhTSH proved to be a highly pure product. Significantly higher endotoxin levels could be detected in all bTSH products compared to the rhTSH.
  
  
  CONCLUSIONS
  Both bTSH products are crude mixtures and therefore not an acceptable alternative to rhTSH. Their use should be discouraged to prevent unintended side effects.
authors.affiliation: Clinic for Small Animal Internal Medicine Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
authors.forename: Sandra
authors.initials: S
authors.lastname: Schaefer
authors.forename: Paul O
authors.initials: PO
authors.lastname: Hassa
authors.forename: Nadja S
authors.initials: NS
authors.lastname: Sieber-Ruckstuhl
authors.forename: Marion
authors.initials: M
authors.lastname: Piechotta
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Reusch
authors.forename: Bernd
authors.initials: B
authors.lastname: Roschitzki
authors.forename: Felicitas S
authors.initials: FS
authors.lastname: Boretti
mesh_terms: D000818:Animals; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004731:Endotoxins / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D013006:Growth Hormone / Q000032:analysis; D006801:Humans; D007986:Luteinizing Hormone / Q000032:analysis; D013058:Mass Spectrometry / Q000662:veterinary*; D011994:Recombinant Proteins / Q000032:analysis*; D013972:Thyrotropin / Q000032:analysis*; D014020:Tissue Extracts / Q000737:chemistry
chemical_list: D004731:Endotoxins; D011994:Recombinant Proteins; D014020:Tissue Extracts; D007986:Luteinizing Hormone; D013972:Thyrotropin; D013006:Growth Hormone