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20 Cards in this Set
- Front
- Back
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Describe the T4 and TSH profile in Graves disease
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Low TSH
High T4 |
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Describe the T4 and TSH profile in Hashimoto disease
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Early Graves
Low TSH High T4 Late Graves Low T4 High TSH |
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Describe the T4 and TSH profile in a thyrotrope secreting pituitary or hypothalamic tumour
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High T4
High TSH |
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Describe the T4 and TSH profile in a non-secreting pituitary or hypothalamic tumour
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Low T4
Low TSH |
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Which amino acid is used to produce catecholamines?
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Tyrosine
via tyrosine hydroxylase -> DOPA -> catecholamines |
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What type of receptors are adrenoceptors?
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GPCR
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Name three effects of beta-adrenoceptor stimulation
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Heart: ↑contractility and AVN conduction
Kidney: JG cells -> renin BV: SmM relaxation (vessels, bronchi, gut & genitourinary) Other: Glycogenolysis (muscle and liver), lipolysis (adipocytes) Action: activate G prot -> AdenCyc -> ↑cAMP (from ATP) |
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Name three effects of alpha-adrenoceptor stimulation
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BV: SmM contraction
Heart: relaxation Other: inhibit insulin release (pancreas), platelet aggregation, reduced NAd from symp terminal Action: inhibit AdenCyc -> ↓cAMP + ↑[Ca]i (by activation of PLC) |
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What is the net effect of alpha- and beta-adrenoceptors on cAMP?
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alpha -> decrease cAMP
beta -> increase cAMP |
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Describe the pathway from iodine to thyroid hormone
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Iodine consumed converted to I- (iodide) in blood.
Taken up predom by TG, regulated by TSH. Facilitated diffusion into colloid. Thyroglobulin in colloid (protein – many tyrosine residues), iodine binds residues to form monoiodotyrosine/diodotyrosine, catalysed by peroxidase (secretion stim by TSH) ->T4 (90%), T3 (9%), rT3 |
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Which type of cells produce calcitonin? What is calcitonin's function?
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Parathyroid cells
Calcitonin switches off osteoclasts and reduces intestinal calcium uptake to reduce blood calcium levels (counteracts PTH) |
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Which enzyme is responsible for converting T4 to T3?
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Deiodinase/Iodine peroxidase
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What are the key differences of fear from anxiety?
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identifiable/known threat,
fight or flight response (c.f. vigilance), onset usually distinct, course is acute/episodic, rational |
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What are the key features of pathological anxiety?
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no organic cause or relation to substance abuse,
absence of psychosis |
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What test would be used for a patient suspected of having thyrotoxicosis? What additional tests could be done?
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TSH
Free T4 Technitium (functional) Ultrasound (anatomical) |
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How soon after a change in thyroid status would you expect to see a change in TSH levels?
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~4 weeks
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What is T4 generally bound to for transport in blood?
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Thyroxine Binding Globulin
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Which antithyroid drugs are typically used for Grave's disease? What is their action?
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Carbimazole and Propyl-thiouracil (PTU)
block peroxidase, prevent organification of iodide and coupling of iodotyrosine residues to form T3 and T4. PTU also inhibs deiodinase (T4->T3) |
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What is the absolute contraindication for radioiodine?
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Pregnancy?
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Which hormone is used in replacement therapy for hypothyroidism?
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T4
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