Polydipsia: Causes of Excessive Thirst

What Is Polydipsia: Definition

Polydipsia means excessive thirst [from Greek poly = much; dipsia = thirst], which is defined as drinking at least 100 mL of water per kilogram of body weight per day, which would be 7 liters per day for a 70 kg person ²⁸. Excessive thirst developing within hours/days is usually due to dehydration. Stronger thirst continuing for a prolonged time may result from an underlying disease, such as diabetes mellitus.

Polydipsia can be either the cause or result of excessive urination (polyuria).

A related condition is beer potomania.

A. Causes of Excessive Thirst WITHOUT Excessive Urination

1. Dehydration due to:

Excessive sweating (diaphoresis)
Diarrhea
Large loose stools after eating foods high in fiber
Hyperventilation due to anxiousness, certain diseases, such as pneumonia, or at high altitudes.
References: ^1,3

2. Dry mouth by causes other than dehydration:

Acute (sudden) causes of dry mouth:

Eating dry or spicy or salty foods
Breathing dry air, breathing through the mouth, snoring, smoking, chewing tobacco
Anxiety, depression, stress ⁴⁵
Hangover
Disorder of salivary glands (mumps, side effect of irradiation) ⁴²
Stroke ⁴²
Shock (hypovolemic, septic, anaphylactic)

Chronic causes of dry mouth (xerostomia):

Anemia
Hypertension
Oral thrush caused by fungal [candida] infection
Disorders of salivary glands (sialadenitis, stones)
Autoimmune diseases: Sjögren’s syndrome, systemic lupus erythematosus (SLE), systemic sclerosis, sarcoidosis (neurosarcoidosis), rheumatoid arthritis
Parkinson’s disease
HIV/AIDS
Alzheimer’s disease
Mouth or throat cancer
Cystic fibrosis
References: ^37,42

Dry mouth as a side effect of medications or supplements:

Anti-acne drugs: isotretinoin, tretinoin ⁴²
Anticholinergics (spasmolytics): atropine ⁴⁷
Antidepressants: fluoxetine
Antidiarrheals: bismuth subsalicylate, loperamide ⁴²
Antiemetics (drugs to treat nausea/vomiting): chlorpromazine, metoclopramide, ondansetron, promethazine, scopolamine ⁴²
Antihistamines ⁴²
Antiepileptics: valproate, topiramate ⁴²
Antiparkinsonians ⁴²
Antipsoriatics: acitretin ¹⁹
Antipsychotics: modafinil, phenothiazines, risperidone, indapamide
Antivirals: ritonavir, indinavir; antiretrovirals (to treat AIDS) ⁵
Aspirin overdose ¹⁵
Beta-blockers (for heart disease, hypertension): atenolol, propranolol ³⁷
Bronchodilators (to treat asthma): theophylline, salbutamol ⁴²
Chemotherapeutics: bortezomib, cisplatin ²²
Muscle relaxants ⁴²
Nasal decongestants (sprays) ⁴²
Non-steroidal anti-inflammatory drugs (NSAIDs): aspirin, diclofenac, ibuprofen, naproxen 51
Opiates: morphine ⁴³
Sedatives (sleeping pills: diazepam) ⁴²
Steroids
Stimulants: armodafinil ⁵⁰

Illegal Drugs:

Marijuana (cannabis) ⁴⁸
Ecstasy (MDMA) ⁴²
Cocaine ⁴⁸
Heroin ⁴⁸
Amphetamine ⁴⁸

B. Causes of Excessive Thirst AND Excessive Urination

Psychogenic Polydipsia

In most cases of polydipsia, people drink water to replace the water they have lost due to excessive urination caused by certain organic disorders. Individuals with primary or psychogenic polydipsia (often associated with schizophrenia) have no organic disorder, but they believe or feel they should drink a lot of fluid. This can lead to water intoxication (hyponatremia), which can be life-threatening.

Brain Disorders Resulting in Central Diabetes Insipidus

Head injury, tumor, stroke ^7,8

Impaired Kidney Function Resulting in Nephrogenic Diabetes Insipidus

Salt-wasting nephropathy (in a polycystic kidney disease), post-obstructive diuresis (after resolution of urinary tract blockage) ²⁰, medullary kidney cystic disease ^¹,proximal renal tubular acidosis ¹

Heart Disorders

Supraventricular tachycardia (a type of heart arrhythmia) ²⁹, postural hypotension, systemic capillary leak syndrome ¹

Hormonal Disorders

Gestational diabetes insipidus; in the 3rd trimester of pregnancy ⁴⁴
Adrenal hyperactivity ^10,^11,35
Epinephrine (adrenaline)-secreting tumor (pheochromocytoma) in the adrenal medulla ¹³
Pituitary disorders:
- Cushing’s syndrome ³⁴
- Sheehan’s syndrome (pituitary infarct)
Hyperthyroidism, especially acute severe thyrotoxicosis (thyroid storm) (hyperglycemia, excessive sweating and diarrhea lead to polydipsia)
Hyperparathyroidism ¹⁷

Metabolic Disorders

Hypokalemia ^20,23
Hypercalcemia ²²
Hypernatremia ²⁴

Genetic and Congenital Disorders

Aceruloplasminemia ¹
Alsing syndrome ¹
Bartter’s syndrome
Boichis syndrome ¹
Cystinosis
DEND syndrome ¹
EAST syndrome ¹
Fanconi syndrome ²¹
Froelich’s syndrome ¹
Gitelman syndrome
Liddle’s syndrome
Nephronophthisis ¹
Schroeder syndrome
Wolfram (DIDMOAD) syndrome
Apparent Mineralocorticoid Excess Syndrome ¹

Other Disorders

Adiposogenital dystrophy
Langerhans cell histiocytosis ¹
Omega-3 FFA deficiency syndrome
Sarcoidosis (neurosarcoidosis) ¹⁸
Tumors/cancers:
- Adrenal adenoma ¹⁰
- Ganglioblastoma
- Glucagonoma — glucagon secreting tumor (gluconeogenesis > hyperglycemia > polydipsia) ¹⁶
- Multiple myeloma ²²
- Pheochromocytoma ¹³

Drugs

Amphotericin B ²²
Antiobesity drugs: lorcaserin, orlistat, phentermine, sibutramine ^42,46
Caffeine intoxication (excessive coffee or tea drinking)
Demeclocycline ^22,39
Diuretics
Lithium ²²
Vitamin D overdose (hypervitaminosis D) ⁴⁹

Poisons

Acid ingestion
Amanita muscaria (fly agaric) and other toxic mushrooms
Arsine gas
Belladonna-like plant
Bloodroot
Death camas
Horse nettle intake
Jimsonweed/Jamestown weed ingestion
Meadow Saffron plant
Mercury poisoning in children (acrodynia, pink disease)
Yellow jessamine (jasmine poisoning)
Snake bites ³³

Procedures

X-ray, CT or MRI investigations that involve injecting a contrast substance into your vein may be followed by excessive urination and thirst lasting for up to 24 hours ⁵⁸

Pathophysiology

Excessive thirst is usually associated with fluid loss due to:

Excessive sweating (fever, high ambient temperature)
Hyperventilation
Diarrhea
Vomiting
Excessive urination (polyuria)
Bleeding (external or internal)

There are at least four mechanisms by which fluid loss from the body results in thirst ³⁶:

Dehydration, which stimulates osmoreceptors in the hypothalamus
Hypovolemia (low blood volume), which stimulates volume receptors in the right atrium
Hypotension (low blood pressure), which stimulates baroreceptors in aortic and carotid arch
Decreased kidney perfusion, which stimulates renin and this angiotensin 2 release, which stimulates the feeling of thirst in the brain.

Associated Symptoms

Individuals with polydipsia usually complain that they are “always thirsty,” “desperate to drink” and they “urinate a lot.”
Drinking large amounts of fluids, drinking at night (nocturnal polydipsia)
Excessive urination (polyuria; >3 liters urine per day), except in dehydration caused by sweating, hyperventilation, vomiting or diarrhea
Urination at night (nocturia), wetting clothes or bed in children (enuresis)
Symptoms due to dehydration: dry mouth, dry skin, dizziness, fainting, weakness, fatigue
Symptoms of an underlying disease, for example:
- Weight loss in diabetes mellitus and insipidus
- Quick, temporary weight gain (in primary polydipsia or anorexia nervosa — 1 liter of water is 1 kilogram or about 2 pounds)
- Excessive hunger (polyphagia) or loss of appetite in diabetes

Signs

Signs of dehydration: dry mucous membranes, dry, wrinkled skin, decreased skin elasticity (prolonged skin turgor)
Signs of long-term untreated diabetes:
- Eye problems: cataract, papilledema, retinal hemorrhage, visual field deficit
- Peripheral neuropathy: numbness in hands and feet

Diagnosis

A doctor can find a cause of polydipsia from symptoms, signs and laboratory tests.

TABLE: Common causes of excessive thirst with typical symptoms and lab values

CONDITION	SYMPTOMS AND SIGNS (besides excessive urination and thirst)	LAB TESTS
Dehydration	Sudden weight loss, dark urine (decreased, not increased urination)	Decreased 24-hour urine; in mild and moderate d.: normal blood sodium; in severe d.: increased blood sodium
Heat exhaustion or heat stroke	Exhaustion, cool, clammy skin, increased body temperature (in heat stroke: warm skin, body T > 105.8 °F or 41 °C)	Decreased 24-hour urine
Diabetes mellitus ³¹	Hunger or poor appetite, weight loss, extreme fatigue, blurred vision, jock itch, diabetes in family	Increased glucose levels in the blood and urine
Diabetes insipidus (central and nephrogenic) ^22,32	History of brain trauma, surgery or tumor, or a kidney disease	Decreased urine specific gravity and osmolality, increased blood sodium
Diuretics	Dry mouth	Decreased urine specific gravity
Psychogenic polydipsia	Usually in individuals with schizophrenia treated with antipsychotics	Increased 24-hour urine, decreased urine specific gravity and osmolality, sometimes: decreased blood sodium
Adrenal hyperactivity (hyperaldosteronism)	Increased blood pressure	Decreased blood potassium, increased urine potassium, increased blood aldosterone after sodium challenge
Anorexia nervosa	Severely decreased body weight	Mineral and vitamin deficiencies (hypokalemia, low iron, etc.)
Postural (orthostatic) hypotension	Dizziness after raising up, Drop of blood pressure > 30 mm Hg upon standing	Nothing typical
Hypertension ³⁵	Increased blood pressure	Possible increase of blood aldosterone, renin
Anemia ³⁸	Paleness, fatigue, hyperventilation	Decreased RBC or abnormal erythrocytes
Congestive heart failure ³⁶	Chest pain, swollen legs	ECG abnormalities
Liver cirrhosis ^12,40,41	History of alcoholism, poor appetite, loss of weight, spider nevuses	Decreased serum proteins (albumin), increased liver enzymes and bilirubin
Chronic dry mouth (xerostomia) in Sjögren’s syndrome and SLE	Rash, joint pain	Specific antibodies in the blood
Shock (hypovolemic, septic, anaphylactic)	Cool, clammy skin, increased heart rate; in late shock: lethargy, low blood pressure	Septic shock: increased or decreased white blood cells (WBC), increased blood glucose
Ecstasy (MDMA) ³⁵, cocaine, marijuana ⁴⁸	Euphoria	Positive urine drug test
Opiates (morphine, heroin)	Sleepiness	Positive urine drug test

The following part is a bit more technical.

Laboratory Tests in Detail

Blood Tests

Glucose
- Elevated:
  - Diabetes mellitus
  - Cushing’s syndrome
  - Early phase of hypovolemic shock (bleeding)
  - Pheochromocytoma ¹³
Sodium:
- Normal levels (135-145 meq/L):
  - In most cases of dehydration (diarrhea, vomiting, excessive sweating)
  - Within 8 hours of onset of acute bleeding
- Hyponatremia (<135 meq/L):
  - >8 hours after onset of bleeding, when interstitial fluid moves into the intravascular space
  - Sometimes after repeated vomiting or severe diarrhea
  - Water intoxication
  - Diabetic ketoacidosis (usually) ⁹
  - Cerebral salt wasting (head injury, tumor) ²⁶
- Hypernatremia (>145 meq/L):
  - Dehydration (sometimes) ²²
  - Diabetes insipidus ²²
Potassium:
- Hypokalemia:
  - Hyperaldosteronism
  - Anorexia nervosa
  - Hyperthyroidism
- Hyperkalemia:
  - Diabetic ketoacidosis (usually) ⁹
Calcium:
- Hypercalcemia:
  - Hyperparathyroidism
  - Hypervitaminosis D
- Hypocalcemia:
  - Diabetic ketoacidosis (usually) ⁹
CBC:
- White blood cells increased or decreased in sepsis
Hematocrit (HCT):
- Decreased in water intoxication
Blood Urea Nitrogen (BUN):
- Increased in kidney failure
- Decreased in water intoxication
pH
- <7.3 (diabetic ketoacidosis) ⁹
Proteins:
- Hypoalbuminemia in liver cirrhosis, nephrotic syndrome, severe malnutrition
Hormone levels:
- ADH
  - Decreased in central diabetes insipidus
  - Increased in nephrogenic diabetes insipidus
- ACTH may be increased in pituitary adenoma or adrenal hyperplasia
- Cortisol may be increased in adrenal adenoma
- Aldosterone may be increased in adrenal adenoma or primary hyperaldosteronism

Urine Tests

Osmolality
- <200 mOsm/kg in psychogenic polydipsia, diabetes insipidus ²⁷
Specific gravity
- <1.005 in diabetes insipidus
Glucose
- Untreated diabetes mellitus 1 or 2 ⁹
- Pheochromocytoma; rare ¹³
Proteins
- In nephrotic syndrome
Sodium
- >20 meq/L: cerebral salt wasting ²⁶

Treatment

Treatment depends on the cause.

Complications: Water Intoxication

Excessive drinking in combination with low food and hence salt intake (chronic alcoholism, anorexia nervosa, psychogenic polydipsia) may lead to water intoxication with hyponatremia and brain edema. Symptoms may include nausea, vomiting, headache, lethargy, confusion, seizures, coma and eventual death.

References

Polydipsia