Described herein are compositions of Thyroid Stimulating Hormone (TSH), wherein at least one polyalkylene glycol polymer is attached to a carbohydrate site of the TSH. Also described are compositions of mutated Thyroid Stimulating Hormone (TSH) and at least one polyalkylene glycol polymer, wherein the mutated TSH comprises a TSH in which one or more amino acid residues has been substituted with cysteine residue, and the polyalkylene glycol polymer is attached to the mutated TSH at the site of the substituted cysteine residue. Pharmaceutical compositions comprising these TSH compositions and method of treating a thyroid condition in a patient in need thereof, by administering to the patient an effective amount of the pharmaceutical compositions are also described.
