Hypothyroidism: Difference between revisions
Line 12: | Line 12: | ||
==[[Hypothyroidism classification|Classification]]== | ==[[Hypothyroidism classification|Classification]]== | ||
The table below presents a classification of isolated thyroid disorders and its causes based on the classification: | The table below presents a classification of isolated thyroid disorders and its causes based on the classification: | ||
{| class="wikitable" | {| class="wikitable" align="center" style="border: 0px; font-size: 80%; margin: 3px;" | ||
! colspan="2" rowspan="3" | | ! colspan="2" rowspan="3" | | ||
! colspan="3" rowspan="2" |Origin of the defect | ! colspan="3" rowspan="2" |Origin of the defect |
Revision as of 20:31, 12 July 2017
For patient information click here
Hypothyroidism Main page |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]
Synonyms and keywords: Myxedema; myxoedema; thyroid activity decreased; hypothyroid
Overview
Environmental iodine deficiency is the most common cause of hypothyroidism on a worldwide basis (16). In areas of iodine sufficiency, such as the United States, the most common cause of hypothyroidism is chronic autoimmune thyroiditis (Hashimoto’s thyroiditis).Autoimmune thyroid diseases (AITDs) have been estimated to be 5-10 times more common in women than in men.
Classification
The table below presents a classification of isolated thyroid disorders and its causes based on the classification:
Origin of the defect | Causes | ||||||
---|---|---|---|---|---|---|---|
Endagenous causes | Exagenous causes | ||||||
Thyroid | Pituirtary | Hypothalamus | Surgery or radiation | Other causes | |||
Primary hypothyroidism | + | - | - |
|
|
| |
Transient hypothyroidism | + | + | - |
|
|
||
Central Hypothyroidism | Secondary
OR Pituitary originated |
- | + | - |
|
|
|
Tertiary
OR Hypothalamus originated |
- | - | + |
|
|
|
Classification of thyroiditis based on the duration algorythm
Hypothyroidism | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Measure Free T4 and TSH | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Normal T4, Elevated TSH>5.5 | Decresased level of Free T4 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subclinical hypothyroidism | Elevated TSH > 5.5 | Normal TSH level OR Decreased TSH level < 0.2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
• Acute Uncomplicated • Acute Complicated • Chronic • Emphysematous • Xantho- granulomatous | • Acute Uncomplicated • Complicated • Recurrent/ Chronic | • Acute Bacterial • Chronic bacterial • Chronic Inflammatory • Chronic non-inflammatory • Asymptomatic | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Differential diagnosis
Disease | History and symptoms | Laboratory findings | Additional findings | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Fever | Goiter | Pain | TSH | Free T4 | T3 | T3RU | Thyroglobin | TRH | TPOAb | |||||
Primary hypothyroidism | Autoimmune | + | +
Diffuse |
- | + | - | ↑ | ↓ | Normal or ↓ | Normal | N/↑ | Normal | ↑ | Auto antibodies present
(Anti GAD-65 and anti insulin anti bodies) |
Inflammatory | + | + | Normal | |||||||||||
Others | ||||||||||||||
Transient hypothyroidism | + | + | + | + | - | ↑ | ↑ | Normal | Normal | ↑ | Normal | Normal | Acanthosis nigricans | |
Subclinical hypothyroidism | + | + | + | - | + | ↑ | Normal | Normal | Normal | ↑ | Normal | Normal or ↑ | - | |
Central Hypothyroidism | Pituitary | + | + | - | - | - | Normal or ↓ | Normal or ↓ | Normal or ↓ | ↓ | Normal | Normal | Normal | Other hormonal deficiencies |
Hypothalamus | + | + | - | - | - | ↑ | Normal | ↓ | Normal | - | ||||
Resistance to thyroid hormone | - | - | - | - | - | ↑ | ↑ | Normal | Normal | ↑ | Normal | Normal | In hospitalized patients especially in ICU and CCU | |
Steroid therapy | + | - | - | - | + | ↑ | ↑ | Normal | Normal | ↑ | ↑ | N/↑ | Acanthosis nigricans, | |
RTA 1 | - | - | - | + | - | Normal | Normal | ↑ | Normal | ↑ | Normal | Normal | Hypokalemia, nephrolithiasis | |
Glucagonoma | - | - | - | - | - | ↑ | Normal | Normal | Normal | - | Normal | Normal | Necrolytic migratory erythema | |
Cushing syndrome | - | - | - | - | + | ↑ | - | Normal | ↓ | N/↑ | ↑ | Normal | Moon face, obesity, buffalo hump, easy bruisibility |
General feature
Symptoms
Symptoms | Constituitional | Local | Reproductive | Neuropsysiological | Others | Physical exam |
---|---|---|---|---|---|---|
More common | cold intolerance
puffiness decreased sweating coarse skin hypothermia Fever if accompanied by thyroiditis weight gain coarse, brittle, straw like hair with hair loss |
obstructive sleep apnea (secondary to macroglossia) | Females can present with galactorrhea and menstrual disturbances | depression | paresthesia and nerve entrapment syndromes | decreased systolic blood pressure
increased diastolic blood pressure bradycardia pericardial effusion abdominal distension ascites (uncommon) non-pitting edema (myxedema) pitting edema of lower extremities hyporeflexia with delayed relaxation ataxia |
Less common | fullness and pain in the throat and neck | infertility | emotional lability | constipation
Pituitary hyperplasia that can lead to hyperprolactinom |
||
|
blurred vision | macroglossia | ||||
goiter | Attention deficit | periorbital puffiness | ||||
slowed speech and movements | Carpal tunnel syndrome |
- Metabolic abnormalities associated with hypothyroidism include:
- anemia,
- dilutional hyponatremia,
- hyperlipidemia,
- reversible increase in creatinine
Complications
Myxedema coma
Rare, severe form of hypothyroidism, a life-threatening condition
- Altered mental status,
- hypothermia,
- bradycardia,
- hypercarbia, and
- hyponatremia.
- Cardiomegaly,
- pericardial effusion,
- cardiogenic shock, and
- ascites
- commonly occurs in individuals with undiagnosed or untreated hypothyroidism who is subjected to an external stress, such as low temperature, infection, or medical intervention (e.g., surgery or hypnotic drugs)