The following are the most important diseases or complications that can be caused by hyperthyroidism (overactive thyroid):
Eyes and eye appendages (H00-H59).
- Corneal damage due to dehydration in the absence/incomplete closure of the eyelids.
- Optic nerve compression – high pressure on the optic nerve can lead to visual impairment or blindness
Endocrine, nutritional, and metabolic diseases (E00-E90).
- Decompensated thyrotoxicosis (thyrotoxic crisis) – excessively elevated thyroid levels lead to a life-threatening condition; usually stress-associated, such as trauma, infection, or even psychological stress.
- Impaired glucose tolerance in untreated hyperthyroidism.
- Hyperuricemia (increased uric acid levels)/gout
- Hypothyroidism (underactive thyroid gland)
- Hypocholesterolemia – decreased cholesterol content in the blood.
- Iodine-induced thyrotoxic crisis – caused by iodine-containing contrast media and drugs such as amiodarone.
- Lipoprotein (a)-decrease
- Recurrence of hyperthyroidism – recurrence of hyperthyroidism.
Cardiovascular system (I00-I99)
- Heart failure (cardiac insufficiency) – in untreated hyperthyroidism of pregnant women.
- Cardiac arrhythmias
- Supraventricular tachyarrhythmias (cardiac arrhythmias with a rapid pulse of more than 100 beats per minute and an origin of the arrhythmia above the ventricles of the heart)
- Tachyarrhythmia absoluta (TAA; cardiac arrhythmia with a rapid pulse of more than 100 beats per minute and completely irregular heart actions)
- Ventricular tachyarrhythmias (rare; cardiac arrhythmia with rapid pulse of more than 100 beats per minute and an origin of the arrhythmia in the ventricles)
- Atrial fibrillation (VHF): 10-25% of patients with manifest hyperthyroidism have VHF.
- Hypertension (high blood pressure)
- Myocardial infarction (heart attack) [in thyrotoxic crisis].
- Thromboembolic complications [in thyrotoxic crisis]
Musculoskeletal system and connective tissue (M00-M99).
- Osteoporosis (bone loss) – by increasing bone turnover by promoting the activity of osteoblasts (bone-building cells), but especially osteoclasts (bone-degrading cells) and consequently increased bone resorption results.
Neoplasms – tumor diseases (C00-D48).
- Colorectal carcinoma (colorectal cancer) – untreated hyperthyroidism is associated with an increased risk of cancer (adjusted odds ratio (OR) of 1.16)
Psyche – Nervous System (F00-F99; G00-G99).
- Anxiety
- Delirium [in thyrotoxic crisis]
- Myasthenic muscle weakness (weakness of the thigh muscles).
- Pseudobulbar paralysis – disease caused by a lesion of the tractus corticobulbaris (corticonuclearis); clinical picture: dysarthria (speech disorder), impairments of tongue mobility, dysphagia (dysphagia) and hoarseness, furthermore (apparent) affect incontinence (lack of affect control) with forced laughter and forced crying.
- Psychosis
- Stupor (severe clouding of consciousness) [in thyrotoxic crisis].
Pregnancy, childbirth, and puerperium (O00-O99).
- Abortion (miscarriage)
- Premature birth
- Intrauterine growth retardation – pathological (abnormal) delay in the growth of a fetus in utero.
- Intrauterine fetal death (IUFT).
- Low birth weight
- Preeclampsia – new-onset hypertension (high blood pressure) during pregnancy with proteinuria (excretion of protein in the urine; > 300 mg/24 h) after the 20th week of pregnancy.
Symptoms and abnormal clinical and laboratory parameters not elsewhere classified (R00-R99).
- Abdominal pain [in thyrotoxic crisis]
- Fever > 40 °C (common) [in thyrotoxic crisis]
- Icterus (jaundice) [in thyrotoxic crisis]
- Cachexia (emaciation; very severe emaciation).
- Nausea (nausea)/vomiting
- Sinus tachycardia (> 100 beats/minute and electrical excitation in a normal manner in the sinus node).
Digestive system (K00-K93)
- Diarrhea (diarrhea)
Injuries, poisonings, and certain other sequelae of external causes (S00-T98).
- Fractures (bone fractures) – manifest hyperthyroidism increases the risk of hip and vertebral fractures by about 4 times.
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