Thyroid physiology
Hyperthyroidism
Hypothyroidism
Miscellaneous
Black History
100
Thyrotropin releasing hormone is released by the ______ while thyroid stimulating hormone is released by the ________
hypothalamus, anterior pituitary
100
What happens to TSH and free T4 levels respectively in hyperthyroidism
TSH levels are markedly depressed, while free T4 levels are elevated
Normal levels TSH 0.5-5 mIU/L, Free T4 0.7-1.9 ng/dL Free T3 80-220ng/dL
100
Clinical or overt hypothyroidism is confirmed by what levels of TSH and T4
Hypothyroidism complicated between 0.2 and 1.2 percent of pregnancies. It's clinical findings include fatigue, constipation, weight gain, cold intolerance, hair loss, prolonged relaxation of deep tendon reflexes
It is confirmed by high TSH and low T4 levels
100
Some maternal and perinatal outcomes of untreated or persistent hyperthyroidism despite treatment
Preeclampsia, heart failure death, Perinatal outcomes involve preterm delivery. Epilepsy and autism spectrum disorders in children
100
The Black National Anthem
Lift Every Voice and Sing
Poem written in 1900 by NAACP leader James Weldon Johnson. He was a principal in a school in Jacksonville Florida and in 1905 a choir of 500 school children first performed it in honor of Abraham Lincoln's birthday
Mid 1900s, during the Civil Right's Movement it became adopted by the NAACP as the Black National Anthem
200
Changes in thyroid hormone levels in the first trimester of pregnancy
Beta HCG: shares structural similarities to TSH, thus stimulates the thyroid gland to increase thyroid hormone production
Thyroid binding globin: protein that transports thyroid hormone with a high affinity for T4 increases due to estrogen mediated hepatic synthesis of TBG, as well as an increase in it's half life
Decrease in TSH, and increase in TBG and total T4 and a decrease in Free T4
200
Treatment of hyperthyroidism contraindicated in pregnancy
Thyroid ablation with therapeutic radioactive iodine is contraindicated in pregnancy as this can cause fetal thyroid gland destruction, thus when radioactive iodine is given unintentionally, some clinicians recommend abortion.
It is recommended for women to avoid pregnancy for 6 months after radio ablative therapy.
During lactation, the breast can concentrate a large amount of radioactive iodine which can pose neonatal risk as well as maternal risk from breast irradiation. As such it is recommended to delay radio ablative therapy until 3 months after breast feeding cessation to ensure complete breast involution
200
Four clinical features of hypothyroidism
Symptoms: cold intolerance, weight gain, constipation, weakness, infertility
Exam: dry skin, edema, decreased deep tendon reflexes, hoarseness
Lab: hyperlipidemia and hyponatremia
Other clinical signs: bradycardia, hypertension
200
Pathophysiology of a thyroid storm
Thyroid storm is an acute life threatening complication of hyperthyroidism with multi system involvement. Some precipitating factors include recent illness, parturition, abrupt discontinuation of thyroid meds, surgery, DKA, trauma, or hyperemesis gravid arum.
In thyroid storm, there is hyperactivity of the sympathetic nervous system, increase in response to catecholamines, and intense metabolic activity leading to an increase in oxygen demand which can induce heart failure, arrhythmias, delirium, seizures and comas
A key presenting factor is a fever greater than 104 plus diaphoresis. Tachycardia greater than 140, pulmonary and peripheral edema, hypotension, agitation and psychosis
200
The date of Juneteenth
Emancipation Proclamation took effect on January 1st 1983, for two years about 250,000 Africans remained enslaved in Confederate Texas.
On June 19th 1865, the army came to Galveston Texas, an announced that all the enslaved Black people in the state were free by executive decree.
300
Organ systems are affected by the thyroid hormone
Heart: Cardiac output, stroke volume, resting heart rate through positive chronotropic and inotropic effects by increasing myocardial intracellular calcium
Circulatory system: Normalizes arterial oxygen concentration and promotes oxygen delivery to tissues, Maintains peripheral vascular resistance
Nervous system: involved in fetal brain development, stimulates the brain to increase wakefulness, alertness, response to external stimuli and peripheral reflexes
Reproduction and other endocrine fxns: Plays a role in ovulation and spermatogenesis. Affects release of other hormones of the pituitary gland
300
Pathophysiology of Grave's disease
Grave's is the overwhelming cause of thyrotoxicosis in pregnancy.
Thyroid stimulating immunoglobulin (TSI), also known as thyroid stimulating antibody (TSAb) are synthesized by B lymphocytes within the thyroid cells, lymph nodes or bone marrow. They bind to thyroid stimulating hormone causing both thyroid hormone synthesis and thyromegaly.
Diagnosis is made by low TSH levels, elevated T4 and T3 levels, Thyroid receptor antibodies, radioactive iodine uptake scan will show diffuse increase in uptake and thyroid ultrasound will show a hyper vascular thyroid
300
Post partum thyroiditis
A transient autoimmune thyroiditis found in approximately 5-10 percent of women during their first year after birth characterized by hyperthyroidism, hypothyroidism or both. About 50% of women with thyroid antibodies during pregnancy will develop postpartum thyroiditis.
Presentation occurs in two phases, with the first phase characterized by destruction induced thyrotoxicosis and symptoms of hyperthyroidism. Thionamides are ineffective. Second phase is hypothyroidism due to thyroiditis. Levothyroxine is given for 6-12 months.
300
Treatment of thyroid storm
I C U !!!!!
Give iodine and corticosteroid to inhibit peripheral conversion of T3 to T4. If iodine allergy, use lithium carbonate.
300
Tuskeegee Experiment
Tuskegee Study of Syphilis in the Negro Male was conducted between 1932 and 1972 by the United States Public Health Service and the CDC. The study enrolled about 400 African American sharecroppers in Tuskegee, Alabama with syphilis . The purpose was to observe the effects of the disease, if left untreated. The participants were not informed of the intent of the study, some were never informed of their syphilis diagnosis, and provided disguised placebos even after the treatment of syphilis with penicillin was available.
The researchers believed that effects of syphilis depended on race, and that tertiary syphilis had more pronounced effects of African American's cardiovascular than nervous system. They also believed they were not harming the men as they were unlikely to ever receive treatment.
Many died, infected their partners or had children born with congenital syphilis. In 1997 President Clinton formally apologized on behalf of the US government for the study
400
Fetal thyroid tissue beings to concentrate iodine at ____ weeks
Fetal thyroid tissue begins to concentrate iodine at 10-12 weeks and synthesis + secretion of thyroid hormone by fetal pituitary TSH starts at approximately 20 weeks.
Before that, the fetus relies on maternal T4 which crosses the placenta at small quantities to maintain normal fetal thyroid function and for normal fetal brain development. At birth, approximately 30% of T4 in the umbilical cord are of maternal origin
400
A thionamide preferred during the first trimester
Propylthiouracil, crosses the placenta less readily
It works by preventing the conversion T4 to T3. Main side effects include hepatotoxicity and transient leukopenia which doesn't require therapy cessation
Agranulocytosis on the other hand requires immediate drug cessation and will usually present as a fever, or cough, or sore throat.
The dosing is 50-150mg orally three times a day depending on the clinical severity. Measure free T4 concentrations every 4-6 weeks
400
The most common cause of hypothyroidism in pregnancy and its pathophysiology
Hashimotos. Characterized by glandular destruction by TPO autoantibodies.
ACOG recommends 1-2 ug/kg/d or approximately 100ug daily and dosing is adjusted by 25-50ug increments until TSH values are around 2.5
Surveillance is by measuring TSH levels every 4 weeks is recommended
Of note, maternal TSH-receptor blocking antibodies can cross the placenta and cause fetal thyroid dysfunction. About 28-47% of fetus' born to mothers with immune thyroiditis will have elevated TPO antibodies by day 15 of life but these antibodies were undetectable by 6 months.
A 2016 study concluded that maternal TPO antibodies have no clinically relevant effects on the thyroid function of the offspring
400
Mechanism of action of methimazole
A thionamide that works by inhibiting thyroid peroxidase
It crosses the placenta more readily than propylthiouracil and is associated with a rare methimazole embryopathy which is characterized by esophageal or chonal atresia and aplasia cutis
Dosing is 10-20mg orally followed by a lower maintenance dose of 5-10mg daily. If you are switching from PTU to methimazole, the dose ratio of 20:1 is recommended
400
Divine Nine Organizations
9 Black Greek Organizations founded on college campuses in the 1900s by Black college students in response to racial segregation and disenfranchisement that denied Black students entry into previously establish white fraternities and sororities.
The organizations allowed the students to forge familial ties to one another and outreach within the larger Black community.
Today, the Divine Nine continues to have an impact on communities through service and civic engagement.
Alpha Phi Alpha Fraternity Inc.
Alpha Kappa Alpha Sorority Inc.
Delta Sigma Theta Sorority Inc.
Kappa Alpha Psi Fraternity Inc.
Phi Beta Sigma Fraternity Inc.
Omega Psi Phi Fraternity Inc.
Zeta Phi Beta Sorority Inc.
Sigma Gamma Rho Sorority Inc.
Iota Phi Theta Fraternity Inc.