What is Polyuria -What are the causes of Polyuria?
What Is Polyuria?
Polyuria is a medical condition characterised by plenty of volumes of urine discharge from the body. The amount of urine passage is around 2.5 litres over 24 hours in adults. Discharging excess fluid from the normal amount requires special attention as it indicates some serious medical problems. Some possibilities can include bladder conditions, urinary tract infections or prostate conditions. It can also be caused due to some metabolic conditions as Type-1 and Type-2 diabetes.
The condition is usually found in occurrence with polydipsia. Polydipsia is occurrence of increase thirst. Although both can occur the other ways. Polydipsia can also be the cause or an effect of polyuria.
Causes Of Polyuria:
There are various causes of Polyuria or the high urine production symptom -
- Excessive intake of fluids, especially water.
- Diuretic foods and drugs – diuretic foods and beverages include caffeine as coffee, tea, chocolate, soft drinks, acidic juices, spicy foods, protein shakes and alcoholic beverages.
- Diabetes mellitus
- Diabetes insipidus
- High doses of Vitamin B2 and C
- Cold diuresis
- Altitude diuresis
- Interstitial nephritis and Cystitis
- Reactive arthritis
- Congestive heart failure
- Cushing’s syndrome
- Addison’s disease
- Conn’s disease
- Urinary tract infections
- Cerebral salt-wasting syndrome
- Postural orthostatic tachycardia syndrome
- Renal glycosuria
- Liver failure
- Neurologic damage
- Post supraventricular tachycardia
- Removal of urinary obstruction
- In addition to these causes, there are certain medications which can also cause excessive urination. Example- Rondomycin and Methacycline can cause Polyuria as a side-effect.
Frequent urination or polyuria is a characteristic symptom of both diabetes mellitus and diabetes insipidus though for entirely different reasons. The urine in diabetes mellitus tastes sweet because of discharge of excess glucose (mellitus meaning being sweet), whereas, it is tasteless in diabetes insipidus and hence the name insipidus. Here is more about diabetes and polyuria.
Polyuria And Diabetes:
- Both the types of diabetes i.e., Diabetes mellitus and Diabetes insipidus cause polyuria or excessive urination.
- Diabetes insipidus is a disorder of urine concentration.
- Hyperglycemia or high glucose level in the body is caused due to Type-1 diabetes mellitus and Type-2 diabetes mellitus.
- Hyperglycemia causes excessive urine production.
- Kidney contains nephrons, which are functional units and perform filtration process.
- There is a bulk water flow in filtration and some useful substances are sent back to the extracellular fluid for re-absorption process.
- Glucose re-absorption contains transport proteins which require specific binding.
- In a diabetic patient having hyperglycemia, the filtered level of glucose exceeds the kidney tubules capacity to reabsorb glucose.
- Hence, urine gets concentrated as the transport proteins become saturated.
- This results in higher glucose level in urine and glucose is a solute which draws water into the urine by osmosis. Hence, hyperglycemia causes a diabetic patient to release glucose concentrated urine.
Polyuria in Diabetes Mellitus
Type 1 Diabetes Mellitus
- In type 1 diabetes mellitus, the inability of pancreas to synthesize insulin will result in high blood glucose levels which results in frequent urination to remove the excess glucose.
Type 2 Diabetes Mellitus
- In type 2 diabetes mellitus, the body cells grow resistant to insulin and do not absorb the glucose present in blood. This results in increase in blood sugar levels after food consumption and frequent urination.
Gestational Diabetes Mellitus
- Polyuria as a symptom in gestational diabetes occurs because of deficiency of and inadequate response to insulin during pregnancy. This causes high blood sugar and thus, polyuria.
Polyuria in Diabetes Insipidus
Central/Neurogenic Diabetes Insipidus
- Central diabetes insipidus is a result of lack of antidiuretic hormone (ADH) secretion by the brain. The hormone is responsible for controlling removal and retention of body fluids. In the absence of this hormone, kidneys tend to filter excess amounts of water from the blood resulting in polyuria.
Nephrogenic Diabetes Insipidus
- In nephrogenic diabetes insipidus, the kidneys are unresponsive to ADH. This results in filtering of water from the blood in excess and so, excessive urination.
Dipsogenic Diabetes Insipidus
- Dipsogenic diabetes insipidus is a result of damage or defect in the thirst mechanism. This causes abnormal increase in thirst and the brain will not release ADH as it needs the excess fluids drained out of the body resulting in polyuria.
Gestational Diabetes Insipidus
- A hormone called vasopressinase produced during pregnancy breaks down the antidiuretic hormone resulting infrequent urination.
Reasons behind Polyuria in Diabetes
Reasons in Diabetes Mellitus
- Diabetes mellitus is caused either because the body is unable to respond to insulin properly causing insulin resistance or because the pancreas cannot produce insulin causing insulin deficiency. Since, insulin is the hormone that regulates blood sugar levels in the body, this function is severely impaired in diabetics, unless diabetes is in control.
- When there is excess amount of glucose (sugar) present in the blood, the kidneys try to filter it out to protect the body from the effects of hyperglycemia. So, when the blood sugar levels are high, there will be frequent urination till the sugar levels come back to normal.
Reasons in Diabetes Insipidus
- Unlike diabetes mellitus, in diabetes insipidus, there is either a deficiency of antidiuretic hormone (ADH), or the kidneys do not respond to ADH, or due to overconsumption of water as a result of defective thirst mechanism, or due to pregnancy in some women. Antidiuretic hormone is responsible for maintaining fluid balance in the body by stopping the kidney from discharging water from blood.
- So, in people with diabetes insipidus, polyuria is due to inability to concentrate urine or removing excess water present in the blood due to over consumption.
Treatment for Polyuria:
Some possible treatment options for Polyuria are-
- Sulfonylurea agents