Diabetes insipidus

Introduction

Diabetes is the most common disease in adults and the elderly however bad lifestyle and modernization has opened its doors for children also. In general, diabetes refers to diabetes  mellitus instead of diabetes insipidus. Diabetes insipidus Hormonal derangement therefore, it is no where related to the blood sugar level. Moreover, it is a his not as chronic as the diabetes mellitus. Diabetes insipidus is the disorder linked with  ADH hormone deficiency. ADH malfunctioning may be the result of injury or infection of the posterior lobe of the pituitary gland where adrenaline is secreted.  The disease mechanism of diabetes mellitus and diabetes insipidus differ in many ways, nonetheless few of the symptoms seems to be similar. Diabetes mellitus is purely related to faulty insulin synthesis and secretion, whereas the diabetes insipidus is the absence or lesser secretion of ADH (vasopressin). The 4 important types of diabetes insipidus are central, nephrogenic, dipsogenic and gestational. Diabetes insipidus affects about 1 in 25,000 people in the general population.

 

Causes of Diabetes insipidus

Diabetes insipidus is known to be idiopathic in most of the cases as the exact cause is still unclear but the disease is  correlated with the conditions that affect the functioning of the hypothalamus( pituitary region). Trauma and infections of hypothalamus head injury, brain tumor,  complications of surgeries of the nervous system, chronic exposure of pituitary gland to radiation and infections of the central nervous system (meningitis, encephalitis, tuberculosis) may predispose a person. Some of the lymphomas, cancers of breast or lung may also increase the risk. Physiologically it is connected to the  abnormal renal absorption and secretory functions  where renal tubules fail to respond to ADH.

 

 

Role of kidneys in fluid regulation

 

Each day, the kidneys  filter about 120 to 150 quarts (ca. 170 litre) of blood. As a result,in a day, 2.27 liters of urine is produced approximately . Normally, our body regulates fluids by maintaining a balance between the intake and output. In a patient suffering from diabetes insipidus, ADH fails to respond properly. Therefore, the tubular reabsorption of distal tubules(tail end of renal tubules) may be depleted . Therefore, there is excessive removal of fluid from our body systems through urination. This is because ADH signals the kidneys to absorb the limited quantity of fluid from the bloodstream, resulting in more fluid loss in the form increased frequency.

 

Signs and Symptoms

In the absence of action of ADH, renal tubules fail to control the excessive water loss in the form of urination. Urine in a diabetes insipidus case appears light-Colored and the specific gravity of the urine ranges around 1.001 to 1.005 which is way too less than the usual. Additionally, a typical case of diabetes insipidus excretes as high as 4-18 liters of urine  in 24 hours at the frequency of at least  every 3o minutes once. Furthermore, the patient often feels thirsty, urgency for urine, hungry ( polydipsia, plyurea and polyphagia) and tired.  The disease can occur in as early as preschool age however risk more for adults. The symptoms cannot be controlled by reducing fluid intake as the  loss of urine continues despite any attempts to maintain the oral fluids. Patient may show the signs of electrolyte imbalance such as tremors in the legs, weakness, increased heart rate, increased muscle spasm and tightness, confusion, dizziness, sluggishness of personal appearance. In order to confirm the diagnosis, blood sugar levels must be checked. If the condition is diabetes mellitus, the blood sugar levels are usually high whereas diabetes insipidus is not linked with the blood sugar levels.

 

Diagnostic criteria

The principal criteria for identifying the diabetes insipidus is the history of increased frequency and the amount of urination beside excess fluid intake. Another important finding is, a diabetes insipidus patient loses at least 3% to 5% of the body weight in a quick time. In addition to these, the specific gravity of urine is also disturbed, however, the urine sugar levels remains nil (which we can see in diabetes mellitus cases). A temporary rise in the levels of serum sodium and plasma levels of ADH (vasopressin) and the urine osmolality provides sound evidences to the diagnosis. 

 

Tips to manage diabetes insipidus

It is not a good idea to stop the fluid intake abruptly , instead the main objective of the treatment is to bring a balance in the ADH levels in the body.  So, ensure that the patient takes enough fluids until the actual cause is treated. It is not an emergency medical condition, however, treating the condition early can result in a good outcome. Doctors prescribe ADH or vasopressin supplements until the patient regains his normal cycle of water balance. Daily urine output should be  tracked to see if there is a progress in the disease condition. Symptomatic management should be initiated to treat tiredness, weakness and weight loss. It is also advisable to cut down the dietary  salt and protein  as this can help kidneys to produce less urine. In most of the cases, treatment can be given at the outpatient department or home and very rarely patients get admitted to the hospital. Regular follow-up, at least once in 15 days is essential to see the changes in the patient’s conditions.

 

Differences between diabetes insipidus and diabetes mellitus

Criteria

Diabetes Insipidus

Diabetes Mellitus

Nature of illness

Chronic but not life-threatening

May be life-threatening if it is not properly controlled.

Pathologic source

Impaired or decreased secretion of adrenaline hormone

Impaired or decreased secretion of insulin hormone

Treatment

Depends upon pills, or self-treatment protocols and restriction of salt in the diet .

Diet, exercise, insulin and lifestyle management

Cause

There are many causes and types of this condition but mostly  it is caused by a hormone imbalance.

Type 1 - Autoimmune Disease; Type 2 - Genetics, lifestyle, infection

Symptoms

Frequent/excessive urination, excessive thirst, and headaches

High blood sugar, excessive urination, increased thirst, increased hunger.

Incidence

3 in every 100,000 Individual

770 in 100,000 individuals

Prognosis

No effect on life expectancy

Up to 10 years shorter life expectancy

Curable

No

No

 

Read more

1.    

ADH

2.

Fluids and electrolyte balance in our body

3.

The urinary system

4. 

Pituitary gland pituitary hormones

 

Important questions

  1. What is the difference between diabetes insipidus and diabetes mellitus?

  2. Explain the role of ADH in diabetes insipidus.

  3. What are the symptoms of diabetes insipidus?

  4. What is the average amount of urine output in an adult per day?

  5. What causes ADH imbalance?

  6. Distinguish between DM and DI.



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