Optimal maintenance levels should be adjusted individually to obtain normal serum T3, T4, free T4, index and Thyroid Stimulating Hormone (TSH) values after several weeks of therapy for hypothyroidism. Close observation of the patient, with individual adjustment of the dosage as needed, is recommended. IV/IM: Administer 50% of PO dose. A daily maintenance dose of 50 to 100 mcg parenterally should suffice to maintain the euthyroid state, once established. Levothyroxine Sodium for Injection produces a predictable increase in the reservoir level of hormone with a seven day half-life. Thyroid 2014; 24: 1670-751.3. An exception may be seen in congenital hypothyroidism where elevated serum TSH values may persist for the first two to three years of life despite normalization of free T4 measurements. PLEASE READ THE CAREFULLY BEFORE ACCESSING OR USING THIS SITE. The thyroid hormones exert the metabolic effects involving normal metabolism, promoting gluconeogenesis and stimulating protein synthesis. Patients unable to swallow intact tabs. In myxedema coma or stupor, without concomitant severe heart disease, 200 to 500 mcg of Levothyroxine Sodium for Injection may be administered IV as a solution containing 100 mcg/mL. clinical judgment in this situation may dictate smaller IV doses of Levothyroxine Sodium for Injection. In the presence of concomitant heart disease, the sudden administration of such large doses of Lthyroxine IV is clearly not without its cardiovascular risks. Jonklaas J, Bianco AC, Bauer AJ, et al. The 2014 American Thyroid Association (ATA) Guidelines recommend initiating levothyroxine as the first line treatment for primary hypothyroidism. Lexicomp. Although measurements of normal blood levels of thyroxine in patients on oral replacement regimens frequently coincide with clinical impressions of normal thyroid status, higher than normal levels occur occasionally and should not be considered evidence of overdosage per se. In all cases, clinical impressions of the well being of the patient take precedence over laboratory determination of appropriate individual dosage. An additional 100 to 300 mcg or more may be given on the second day if evidence of significant and progressive improvements has not occurred. Administer oral levothyroxine >4 hr apart from drugs known to interfere with absorption. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.The authors make no claims of the accuracy of the information contained herein; and these suggested doses and/or guidelines are not a substitute for clinical judgment. Accessed February 7, 2019.2. Dickerson RN, Maish GO, Minard G, et al. Continuous daily administration of 50 to 100 mcg IV should be given until the patient is stabilized, and oral administration is feasible. The dose conversion has been updated in the ATA Guidelines, which recommend a dose conversion of 0.75:1 when converting from a parenteral to enteral route. Neither GlobalRPh Inc. nor any other party involved in the preparation of this document shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material. Historically, when converting from a parenteral to enteral route, the dose conversion was 1:2. 1. Based on this data, the ATA Guidelines and Lexicomp recommend administering an IV dose that is 75 percent of the oral dose when converting from a parenteral to enteral route. ... Also prescribed as Levothyroxine, Levothroid, Tirosint, Levoxyl, Unithroid, Novothyrox. Although the patient may show evidence of increased responsivity within six to eight hours, full therapeutic effect may not be evident until the following day. The patent’s clinical status is most important and some patents may be clinically euthyroid with individual laboratory values that are not within normal range (i.e., elevated total T4 with normal T3). Levothyroxine is available in both an oral and intravenous (IV) formulation. Lexi-Drugs. Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Levothyroxine (Synthroid ®) is a synthetic form of thyroxine, which is an endogenous hormone secreted by the thyroid gland.Thyroxine (T 4) is converted to the active thyroid hormone, L-triiodothyronine (T 3).The thyroid hormones exert the metabolic effects involving normal metabolism, promoting gluconeogenesis and stimulating protein synthesis. In infants and children, there is great urgency to achieve full thyroid replacement because of the critical importance of thyroid hormone in sustaining growth and maturation. Clinical Relevancy of the Levothyroxine-Continuous Enteral Nutrition Interaction. )