Elephant specific information, if available, is in blue.

Chemistry – Obtained from bovine anterior pituitary glands, thyrotropin is a highly puri­fied preparation of thyroid-stimulating hormone (TSH ). Thyrotropin is a glycoprotein and has a molecular weight of approximately 28,000 – 30,000. Thyrotropin is measured in International Units (IU), with 7.5 micrograms of thyrotropin approximately equivalent to 0.037 units. Commercially available thyrotropin is available as a lyophilized powder for reconstitution and is practically free of any adrenocorticotropic, somatotropic, go­nadotropic and posterior pituitary hormones. Thyrotropin may also be known as TSH, thyrotrophin , thyroid-stimulating hormone  or thyrotropic hormone .

Storage/Stability/Compatibility – Thyrotropin lyophilized powder for injection is report­edly stable in the dry state. However, the veterinary manufacturer recommends storing the powder below 59°F, and after reconstituting, storing in the refrigerator and discarding any unused drug after 48 hours. However, recent information has suggested that reconstituted TSH is stable for at least 3 weeks when refrigerated. The human-approved product may be kept refrigerated (2-8°C) for up to 2 weeks after reconstituting.

Pharmacology – Thyrotropin increases iodine uptake by the thyroid gland and increases the production and secretion of thyroid hormones. With prolonged use, hyperplasia of thyroid cells may occur.

Uses/Indications – The labeled indications for Dermathycin® (Coopers/P/M; Mallinckrodt) is for “the treatment of acanthosis nigricans and for temporary supportive therapy in hypothyroidism in dogs.” In actuality however, TSH is used in veterinary medicine principally as a diagnostic agent in the TSH stimulation test to diagnose primary hypothyroidism.

Pharmacokinetics – No specific information was located; exogenously administered TSH apparently exerts maximal increases in circulating T4 approximately 4-8 hours after IM or IV administration.

Contraindications/Precautions – The veterinary manufacturer (Coopers) lists adrenocor­tical insufficiency and hyperthyroidism as contraindications to TSH use for treatment pur­poses in dogs. In humans, TSH is contraindicated in patients with coronary thrombosis, hypersensitive to bovine thyrotropin, or with untreated Addison’s disease.

Adverse Effects/Warnings – Because the product is derived from bovine sources, anaphy­laxis may occur in patients sensitive to bovine proteins, particularly with repeated use.

Overdosage – Chronic administration at high dosages can produce symptoms of hyperthy­roidism. Massive overdoses can cause symptoms resembling thyroid storm. Refer to the levothyroxine monograph for more information on treatment.

Drug Interactions; Drug/Laboratory Interactions – For reference, refer to the informa­tion listed in the Levothyroxine monograph for more information.

Doses –

Horses:

For TSH stimulation test:

a)   Draw pre-dose sample, then 5 – 10 IU of bovine TSH IV. Draw follow-up sam­ples 4-8 hours after dosing. Normal thyroid gland should produce a 2-4 times increase in serum T3 and T4 levels. (Chen and Li 1987)

Client Information – Usually TSH will be used by professional staff. If the drug is to be used at home, the owner should follow directions carefully, shake the vial well after re­constituting, and store in the refrigerator.

Dosage Forms/Preparations/FDA Approval Status –

Veterinary-Approved Products:

Thyroid Stimulating Hormone (Veterinary) 5 IU per vial (with 5 ml of Water for Injection as diluent); Dermathycin® (Schering Plough); (Rx)  Approved for use in dogs. This product may not be currently on the market.

Human-Approved Products:

Thyrotropin (Thyroid Stimulating Hormone) Powder for Injection 10 IU per vial (with diluent); Thyrotropar® (Armour); (Rx)