Polyuria - Symptoms, Types, Causes & Diagnosis

Polyuria - Symptoms, Types, Causes & Diagnosis

Unreasonably high urine output in comparison to the effective arterial blood volume and serum sodium is referred to as polyuria. Those with polyuria who produce more than 3-3.5 L of urine per day with low urine osmolality (300...

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Unreasonably high urine output in comparison to the effective arterial blood volume and serum sodium is referred to as polyuria. Those with polyuria who produce more than 3-3.5 L of urine per day with low urine osmolality (300 mmol/kg) can have their polyuria objectively measured. Although polyuria is not a disease in and of itself, it might be a sign of other ailments. Diabetes, kidney illness, and particular drugs are common reasons. Moreover, pregnancy, an electrolyte imbalance, too much coffee, and alcohol consumption can all contribute to it.

Two key variables affect the amount of urine produced each day. The first is the volume of excreted solutes each day, while the second is the nephron's capacity for concentrating urine.  A diuresis can result from disturbances in either of these components, which can happen through a variety of different causes. Water diuresis, solute diuresis, or a mix of these processes may be the driving forces behind this diuresis.

What is the Pathophysiology of Excessive Urination?

Water intake, which is subject to complicated regulation in and of itself, renal perfusion, glomerular filtration and tubular reabsorption of solutes, Water homeostasis is sustained by a combination of reabsorption of water from the renal collecting ducts and other processes.

Increased hydration reduces the production of antidiuretic hormone (ADH; also known as arginine vasopressin) from the hypothalamic-pituitary system because it increases blood volume and lowers blood osmolality. Reduced levels of ADH increase urine volume, which enables blood osmolality to return to normal because ADH encourages water reabsorption in the renal collecting ducts.

Furthermore, elevated solute concentrations in the renal tubules result in passive osmotic diuresis (solute di), which raises urine volume.

The most well-known instance of this process is the glucose-induced osmotic diuresis that occurs in uncontrolled diabetes mellitus when high urinary glucose levels (> 250 mg/dL [13.88 mmol/L]) exceed the capacity of the renal tubules to absorb glucose. Water passively follows, causing glycosuria and an increase in urine volume. With the use of sodium-glucose cotransporter 2 inhibitors (SGLT2i), which lower plasma glucose levels by inhibiting renal glucose reabsorption and raising renal glucose excretion, glucose-induced osmotic diuresis in diabetes mellitus is further intensified.

Categories of Polyuria

When it first appears and how long it lasts, polyuria may:

  • Temporary
  • Permanent
  • Transient.

Periodic Polyuria

Sometimes occurring polyuria appears in the patient situations indicated below.

Greater consumption of clear liquids

consumption of foods like watermelon, whisky, and coffee that naturally contain diuretics.

Increased levels of cortisol, adrenaline, and noradrenaline are released into the bloodstream as a result of stressful and emotional circumstances.

Occasionally insignificant factors, such as exposure to cold environments, might increase enuresis.

The most important aspect that is emphasised in all of the scenarios stated above is that polyuria only lasts for a short period.

Polyuria that is Hypotonic and Isotonic

The osmolality and osmolarity of the urine plasma, which is subsequently controlled by the sodium concentration in the plasma, determine the primary distinction between isotonic and hypotonic polyuria.

Hypotonic polyuria is defined as having a urine osmolality below 200 mOsm/100 mL. The following conditions are typically linked to Kidney-related insipidus sweet diabetes.

persistent renal failure pyelonephritis, a condition brought on by polycystic kidney disease

Certain anomalies in sodium and calcium metabolism and electrolytes, such as hypokalemia and hypercalcemia.

Understanding the Origins of Polyuria

Polyuria can have a variety of causes, from excessive water consumption to major medical issues like renal failure. The most frequent causes of polyuria are listed below.

Mellitus Diabetes: Diabetes mellitus is a disorder brought on by the body's failure to effectively regulate blood sugar, either due to improper insulin production or insulin resistance. Due to elevated sugar levels, diabetes mellitus causes the blood to be more osmolar.

Diabetes insipidus: Diabetes insipidus, which has nothing to do with blood glucose levels, is entirely distinct from diabetes mellitus. Instead, due to its association with the antidiuretic hormone arginine vasopressin (AVP), diabetes insipidus is directly associated with polyuria.

A neurological disease results in a lack of arginine vasopressin production, which leads to central diabetes insipidus. Nephrogenic diabetes insipidus results from the kidney's inability to react to AVP. Traumatic or medical brain injuries can lead to central diabetes insipidus. Most cases of nephrogenic diabetes insipidus are hereditary.

Diuretic Drugs: Certain medications are designed to cause you to urinate more frequently to treat conditions including congestive heart failure and high blood pressure. If the dosages are incorrect, those drugs may cause polyuria. To prevent needless urination, your doctor will change the dosage of your medications as necessary.

Lithium: A drug called lithium is used to treat mood disorders. It has a significant impact on the kidneys in people who take it frequently and is virtually eliminated from the body through urine. Lithium can result in nephrogenic diabetic insipidus, which can lead to polyuria and polydipsia.

Intake of Alcohol or Caffeine: Caffeine and alcohol are both recognised diuretics. Excessive consumption of either one can cause polyuria to the point of dehydration. 6 Even for those who regularly consume alcohol, it always has a diuretic effect. Caffeine's diuretic effects can wane with time in those who consume it often.

Pregnancy: Early pregnancy symptoms like polyuria are frequent. Progesterone and human chorionic gonadotropin are what cause it (HCG). Pregnancy polyuria usually goes away after the first trimester.

In the second trimester, polyuria may indicate gestational diabetes. If you are worried about frequent urination while pregnant, talk to your doctor.

What is the Relation Between Polyuria and Diabetes?

Polyuria can happen in patients with diabetes who have been diagnosed if blood glucose levels have gone too high, in addition to being one of the signs of undiagnosed diabetes.

The body will attempt to correct the situation if blood glucose levels get too high by filtering the blood glucose through the kidneys. You will need to urinate more frequently than normal since the kidneys will filter out more water as a result of this.

It may indicate that your sugar levels are too high if you frequently feel a greater urge to urinate. If you are peeing more than usual, you might want to check your blood sugar levels if you have access to blood glucose testing strips.

How Different is Diuresis from Polyuria?

Diuresis: When the kidneys filter too much body fluid, it is called diuresis. As a result, you produce more urine and need to use the restroom more frequently.

Polyuria: The term "polyuria" refers to the frequent passing of huge amounts of urine, or more than 3 litres per day, as opposed to the 1 to 2 litres that people typically pass each day.

In that both diuresis and polyuria require the production of a lot of urine, they are similar. But because of their underlying causes, they are distinct. Diuresis is when the body is forced to produce pee, typically by an external force like a diuretic medicine or herb. Diuresis frequently occurs because it is necessary, typically as a result of the body being overloaded with fluid. Yet unlike diabetes, which is brought on by a disease state and not by an outside factor or medication, polyuria is brought on by a disease state.

What to Look For When Urination Increases Dramatically?

  • Increased fluid intake and thirst: Polyuria is typically accompanied by thirst. The main symptom of psychogenic polydipsia, which is most frequently found in adolescents, is thirst accompanied by compulsive water drinking.
  • Nocturia: This will typically be a sign of real polyuria, though secondary enuresis in kids is possible.
  • Other related symptoms: This increases the possibility of serious pathology and includes symptoms including weight loss, sluggishness, headaches, and shortness of breath.
  • Loss of weight: Type 1 diabetes is characterised by rapid weight loss at first. Chronic renal illness often causes weight loss, which in diabetes insipidus may potentially be the result of dehydration.
  • History of illness: Diabetes mellitus, connective tissue diseases including systemic lupus erythematosus (SLE), renal vascular disease, pyelonephritis, or obstructive uropathy can all lead to chronic kidney disease. Cranial diabetes insipidus can result from head trauma, sarcoidosis, meningitis, pituitary surgery, or radiation treatment.
  • Family background: A history of nephrogenic diabetes insipidus, polycystic kidneys, or diabetes mellitus in the family.

What are the Common Warning Signs?

  • Blood pressure and pulse:  Dehydration may cause tachycardia and postural hypotension, while increased blood pressure and bradycardia may result from elevated intracranial pressure.
  • Eyes: Consequences from diabetes and papilloedema in the event of elevated intracranial pressure (retinal haemorrhages, exudates, new vessel formation, cataracts). A visual field impairment could result from a pituitary tumour.
  • Abdomen: In renal diseases, palpable kidneys.

Diagnostic Workup for Excessive Urine Production

  • Testing urine: Urine testing for indicators of renal illness and diabetes (glucose, ketones) (proteinuria). In diabetes insipidus and psychogenic polydipsia, specific gravity is exceedingly low.
  • Urine osmolality: A plasma osmolality test and an early-morning urine sample. Diabetes insipidus has a high plasma osmolality and an unnaturally low urine osmolality, whereas psychogenic polydipsia has low plasma and urine osmolalities.
  • Measurement of proteinuria:  Urine was collected continuously for 24 hours; ACR for microalbuminuria.
  • Light-chain immunoglobulins (Bence Jones' protein) in urine electrophoresis: myeloma may be the cause of hypercalcemia
  • Blood test: Electrolytes including calcium and potassium, and anomalies that could be signs of chronic renal disease.
  • FBC, ESR: Anaemia is a complication of collagen vascular disorders and chronic renal disease. Infiltration of the bone marrow may be visible in myeloma. ESR increased in myeloma, cancer, and collagen vascular disorders.
  • Tests of pituitary function: If collagen vascular disease is a potential contributor to renal failure, run an autoantibody screen. Serum lithium level, if important.

Importance of Water Deprivation Test in Polyuria?

The water deprivation test aids in the distinction between nephrogenic and central diabetes insipidus. To assess serum electrolytes and osmolality, venous blood is collected early in the morning along with the patient's weight. Also measured is the osmolality of urine.

Every hour, urine is collected, and its osmolality is assessed. The patient is consequently gradually dehydrated as a result of this water deprivation. This keeps happening until postural hypotension and tachycardia appear, until the body weight returns to normal, or until the urine concentration stabilises at less than 30 mOsm/kg in two successive samples. Afterwards, a subcutaneous injection of 5 units of aqueous vasopressin is given.

After an hour, urine is collected to signal the end of the test. Typically, after a vasopressin injection, the urine osmolality does not rise above 5%.

How may Polyuria be Avoided?

It might be challenging to stop polyuria, especially if it has an endocrine or renal cause. But, by controlling fluid consumption, abstaining from alcohol and caffeine, avoiding fluids before night, using diuretics strictly under medical supervision, managing diabetic mellitus, and looking for lithium alternatives in the event of a psychogenic reason, the symptoms can be alleviated.

Some healthy tips:

  • Control your fluid consumption by being conscious of how much you consume each day. Controlling fluid consumption will aid in reducing polyuria's symptoms.
  • Reducing the urge to urinate, and avoiding fluids before bed will help to minimise nocturnal polyuria.
  • Reduce your intake of alcoholic and caffeinated beverages because both of them tend to produce polyuria.

Polyuria Relief: Treatment Approaches and Solutions

The underlying reason is the focus on the best polyuria treatment. For instance, stopping the use of lithium might be used to treat nephrogenic diabetes insipidus. 7 If the patient's blood glucose levels are under control, the polyuria brought on by their diabetes mellitus is likely to become better.

One or more drugs from a variety of classes are frequently used to treat polyuria when the underlying cause cannot be resolved. The fact that the urine produced is diluted and contains more water than urine is a distinguishing feature of polyuria.

Giving a particular type of diuretic, which typically causes an increase in urine production because it enhances urine processing in the kidneys, is one of the treatments for polyuria.

"Stay hydrated, stay healthy - managing polyuria one day at a time."