Endocrine Disorders



Endocrine Disorders





Adrenal Insufficiency

Mary P. White


Background



  • Adrenal glands, located on the kidneys, produce three types of hormones:



    • Glucocorticoid hormones (e.g., cortisol, corticosterone).



      • Maintain glucose control by affecting protein and carbohydrate metabolism.


      • Inhibit glucose uptake in muscle and adipose tissue.


      • Stimulate gluconeogenesis, particularly in the liver.


      • Respond to stress by upregulating the expression of anti-inflammatory mediators and downregulating the expression of proinflammatory mediators.


      • If prolonged exposure to glucocorticoids, Cushing syndrome develops.



        • Obesity, muscle wasting/weakness, decreased glucose tolerance/hyperglycemia, buffalo hump.


    • Mineralocorticoid hormones (e.g., aldosterone, dehydroepiandrosterone).



      • Maintain the balance of sodium and potassium in the body.


      • When aldosterone is increased, aldosteronism develops.



        • Hypernatremia and hyperkalemia, resulting in hypertension.


      • If androgens are increased, sex characteristics will be affected.


    • Sex hormones (e.g., androgens, progestins, and estrogens).


  • Disorders affecting the adrenal cortex lead to inadequate or absent production of hormone(s).


  • Disorders are either congenital or acquired.


  • Adrenal insufficiencies can be acute (adrenal crisis) or chronic (Addison disease).



    • The most common causes of acute adrenal insufficiency are Waterhouse-Friderichsen syndrome, sudden withdrawal of long-term corticosteroid therapy, and stress states in patients with chronic adrenal insufficiency.


Primary Adrenal Insufficiency



Etiology/Types



  • Congenital primary adrenal insufficiency.



    • Congenital adrenal hyperplasia (CAH) is the most commonly identified cause of primary adrenal insufficiency in children.



      • Autosomal recessive disorder: defect in an enzyme (largely, 21-hydroxylase deficiency) required in the synthesis of cortisol to cholesterol.


      • Results in dysfunction in the synthesis of adrenal steroids.


      • Incidence: 1 in 10,000 to 18,000 live births.



        • Females have higher incidence; most commonly diagnosed at birth.


        • Males usually present with a life-threatening salt-wasting crisis in the first month of life.


      • Newborn screen has incorporated CAH testing in most states in the United States, decreasing the time to diagnosis, particularly for males.


  • Acquired primary adrenal insufficiency.



    • Includes autoimmune etiologies (autoimmune destruction of adrenal cortex) and iatrogenic causes such as hemorrhage, trauma, drug effects, pituitary tumor, or infection.


Clinical Presentation



  • CAH.



    • Ambiguous genitalia at birth.


    • If not diagnosed at birth, symptoms will present within 1 to 4 weeks of life.



      • Vomiting, dehydration, cardiac arrhythmias, hyponatremia, hyperkalemia, or salt-losing crisis, resulting in circulatory collapse.


  • Adrenal insufficiency.



    • Symptoms can be slower to progress.




      • Fatigue, loss of weight, hyperpigmentation of the creases of the skin, nausea, vomiting.


      • Prolonged recovery from an illness may prompt further investigation of multiple vague symptoms, leading to the diagnosis.


  • Adrenal crisis.



    • Acute symptoms: life-threatening disorder.



      • Vomiting, abdominal pain, hypovolemic shock.


      • May occur in individuals with chronic adrenal insufficiency experiencing a stressor such as an intercurrent illness, surgical procedure, or in cases of abrupt cessation of glucocorticoid administration.


Diagnostic Evaluation



  • 17-OHP levels; often completed on newborn screening.


  • Morning 17-OHP levels may be elevated in a partial enzyme deficiency.


  • Testosterone level; females (elevated).


  • Androstenedione; males and females.


  • Karyotyping important for ambiguous genitalia.


  • Adrenocorticotropic hormone (ACTH) stimulation test may be necessary to confirm diagnosis.



    • Significant rise in cortisol level 30 to 60 minutes following ACTH injection.


    • Decreased cortisol response also seen in some cases.


Secondary Adrenal Insufficiency




Management: Primary and Secondary Adrenal Insufficiency



  • Glucocorticoid administration.



    • Goal is to replace physiologic glucocorticoid production.



      • CAH: 10 to 20 mg/m2/day of oral hydrocortisone daily.


      • Adrenal insufficiency: 6 to 9 mg/m2/day oral hydrocortisone daily.


    • The dose of glucocorticoid should be adjusted in patients with fever or illness to reflect the normal physiologic response to stress (stressed states result in elevated cortisol levels in a normal host).


    • Stress dosing: hydrocortisone 25 to 50 mg/m2/day IV/IM.


    • For severe illness or surgical procedures, higher doses may be indicated: hydrocortisone 50 to 123 mg/m2/day IV.


  • Mineral corticoid maintenance.



    • CAH and salt-losing forms of adrenal insufficiency: 0.1 to 0.2 mg oral fludrocortisone acetate daily.


    • Infants require 17 to 34 mEq of sodium supplementation daily.


    • Monitor blood pressure and electrolytes.



Cerebral Salt Wasting

Michele Goodwin

Sharon Y. Irving


Background



  • Occurs following an acute central nervous system (CNS) injury.


  • Occurs in the setting of both hypovolemia and hyponatremia.


  • Reports of cerebral salt wasting (CSW) in the pediatric population first appeared in the 1980s.


  • Syndrome of inappropriate antidiuretic hormone (SIADH) is more common than CSW in patients with hyponatremia and CNS disease.


  • It is important to distinguish between SIADH and CSW as treatments for the disorders are different.



Etiology



  • Unclear etiology.


  • Strong association with elevation in the circulating brain and atrial natriuretic peptides, along with an alteration in the neuronal control of the kidneys.



  • May lead to the inhibition of the renin-angiotensin-aldosterone system, causing abnormal renal reabsorption of sodium and triggering the release of antidiuretic hormone (ADH) necessary to maintain intravascular volume.


  • May be associated with the following clinical conditions:



    • Traumatic brain injury.


    • Intracranial surgery.


    • Meningitis.


    • Encephalitis.


    • Subarachnoid hemorrhage.



Clinical Presentation



  • Headache.


  • Nausea/vomiting.


  • Depressed/altered mental status.


  • Lethargy.


  • Dehydration.


  • Agitation.


  • Seizures.


  • Hypotension.


  • Coma.


  • The rate of renal sodium loss, the degree of hyponatremia, and the overall fluid status impact the severity of the presenting symptoms.


Diagnostic Evaluation



  • Laboratory studies:



    • Serum sodium <135 mEq/L.


    • Serum osmolarity <280 mOsm/kg.


    • Urine sodium >80 mEq/L.


    • Urine osmolarity >200 mOsm/kg.


    • Urine specific gravity >1.010.



    • Urine output 2 to 3 mL/kg/hour.


    • Head CT/MRI.



      • Can identify structural abnormalities/pathophysiologic changes (e.g., arteriovenous malformation, tumor or other space-occupying lesion, hemorrhage).


    • Lumbar puncture.



      • CNS infection (in cases of CNS-infection-triggered CSW).


Management



  • Distinguish between CSW and SIADH.



    • Treatment is different for these conditions.


    • Identify and treat the underlying cause.


    • Frequent monitoring of serum sodium levels and fluid balance.


    • Sodium replacement using a non-dextrose-containing isotonic or hypertonic fluid at an approximate rate of 0.5 to 1 mEq/hour.


    • Limit serum sodium level rise to no more than 10 to 12 mEq/day.



      • The demyelination that occurs with rapid osmotic fluid shifts can result in irreversible neurologic damage.


      • If the patient presented with acute neurologic changes, this may be related to the rate of serum sodium loss.



        • In this instance, it may be more appropriate to provide non-glucose-containing hypertonic fluid until symptoms abate.


    • Consultation with appropriate subspecialty services, including neurosurgery and neurology.


    • Patient/family education regarding CSW etiology, diagnostic testing, and treatment.



Diabetes Insipidus

Allison Thompson


Background



  • A disorder caused by insufficient secretion of ADH by the pituitary gland (neurogenic), or failure of the kidneys to respond to circulating ADH (nephrogenic).


  • Characterized by increased thirst and the excretion of large amounts of dilute urine.


Etiology



  • Neurogenic (central diabetes insipidus [DI]).



    • Genetic: typically X-linked recessive.



      • Examples: Wolfram syndrome.



        • A rare inherited autosomal recessive condition.


        • Affects 1 in 770,000 children.


        • Characterized by central DI, diabetes mellitus, optic atrophy, and deafness.


        • In this disorder, central DI is caused by the loss of ADH-secreting neurons in the supraoptic nucleus and impaired processing within the hypothalamus.


    • Congenital.



      • Often associated with midline craniofacial defects such as holoprosencephaly and septo-optic dysplasia.


    • Acquired.



      • Can result from damage to the pituitary gland or posterior hypothalamus from neurosurgery, trauma, tumors or other brain lesions, meningitis, or encephalitis.


      • May be either a temporary or a permanent disorder depending on the injury.


  • Nephrogenic DI.



    • Congenital.



      • Typically X-linked recessive involving mutations of VR2 or AQP2.


    • Acquired.



      • Variety of conditions that lead to the inability of the kidneys to respond to ADH.



        • Chronic renal failure.


        • Renal tubulointerstitial diseases.


        • Hypercalcemia.


        • Potassium depletion.


        • Sickle cell disease.


      • Medication-induced from drugs, including alcohol, lithium, diuretics, amphotericin B, demeclocycline.


      • Dietary abnormalities.



        • Primary polydipsia.


        • Decreased sodium chloride intake.


        • Severe protein restriction or depletion.


        • Nephrogenic DI that results from a metabolic condition may be reversed if the medication is stopped or the metabolic condition is corrected.


Clinical Presentation



  • Polyuria.


  • Dilute urine.


  • Polydipsia.


  • Inappropriately low urine sodium and osmolality.


  • Urine specific gravity <1.005.


  • Hypernatremia.


  • Serum hypo-osmolality.


  • Dehydration.


Diagnostic Evaluation



  • History and differential diagnoses.



    • The primary causes of polyuria and polydipsia are diabetes mellitus and central DI.


    • Other causes include urinary tract infection, relief of renal obstruction, and psychogenic polydipsia (characterized by excessive water intake).


    • Once hyperglycemia has been excluded, history should include age of initiation and rate of onset of polyuria (will reflect primary vs. secondary cause).



  • Serum laboratory studies.



    • Sodium >150 mEq/L.


    • Osmolality ≥295 mOsm/kg.


  • Urinary laboratory studies.



    • Sodium <30 mEq/L.


    • Osmolality <200 mOsm/L.


    • Specific gravity <1.005.


  • Brain imaging studies.



    • Head CT/MRI.



      • Presence of intracranial mass, abnormal findings of hypothalamic/pituitary stalk.


  • Water deprivation testing.



    • Only performed in acute care setting under close medical monitoring and supervision.


    • Fluids are restricted until as much as 5% of body weight has been lost to evaluate urinary response when the serum osmolality exceeds 295 mOsm/kg.



      • Central DI.



        • Concentrated urine and decreased urine output following ADH administration.


      • Nephrogenic DI.



        • Excessive, dilute urine despite hypernatremia and hyperosmolality.


Management



  • Restore hemodynamics.


  • Replace water deficits and correct electrolyte disturbances.


  • Decrease urine output to within normal range (e.g., vasopressin, desmopressin).


  • Treat underlying condition, when possible.


  • Volume replacement.



    • Maintenance IV fluids, plus mL per mL urine output replacement (usually allow 1-2-mL/kg/hour urine output and replace the remainder).


  • Monitor serum sodium closely.


  • Primary plan for central DI is ADH replacement to control polyuria.



    • ADH preparation depends on acuity of illness and the ability of the patient to tolerate oral intake.


    • Dose varies based on the preparation/formulation and include:



      • Vasopressin.



        • Continuous IV infusion.


        • Used in the critical care or perioperative setting due to its short half-life (10-20 minutes) and easy titration.


        • Initiated at a dose of 0.5 milliunits/kg/hour and titrated until urine output is decreased.


        • Titrated to obtain urine output less than 4 mL/kg/hour.


      • Desmopressin.



        • Used in all other settings.


        • Available in oral and intranasal formulations.


        • Chronic therapy: Dose range is 5 to 30 µg/day, with a peak effect within 1 to 5 hours.


        • Nephrogenic DI is resistant to vasopressin administration (Figure 7.2).






FIGURE 7.2 • Diabetes Insipidus Flowchart.



Diabetic Ketoacidosis

Keshava Gowda

Tageldin M. Ahmed



Epidemiology/Etiology



  • Previous diagnosis of type I diabetes:



    • Insulin dose omission.


    • Intercurrent illness.



      • Stress increases counterregulatory hormone levels, promoting gluconeogenesis and insulin resistance.


    • Unrecognized disruption in insulin pump therapy (if applicable).


  • New onset of type diabetes



Clinical Presentation



  • Polyuria, polydipsia, polyphagia, abdominal discomfort/pain, nausea and vomiting, nonspecific weakness, fruity breath odor, Kussmaul respirations.



    • Severe presentation can include altered mental status, seizures, and coma.


Physical Examination Findings



  • Tachycardia.


  • Decreased pulses.


  • Poor perfusion.


  • Dry mucus membranes.


  • Enophthalmos.


  • Poor skin turgor.


  • Hypotension.


  • Deep or labored breathing.


Diagnostic Evaluation



  • Blood glucose >200 mg/dL, serum pH <7.3, bicarbonate <15 mmol/L.


  • Serum electrolytes, blood urea nitrogen (BUN), creatinine, calcium, magnesium, phosphorus.


  • High serum osmolality.


  • Positive serum/urine ketones.


  • Hemoglobin A1C.


  • Complete blood count with differential.



    • Leukocytosis is not a reliable marker of infection.


    • Elevation in stress hormones may mimic infection.


  • Autoimmune markers.



    • GAD-65 (glutamic acid decarboxylase), IA-2, IA-2β.


    • Insulin auto-antibodies.


    • May be evaluated for evidence of associated autoimmune conditions.


Management



  • Monitoring.



    • Cardiac monitoring.



      • Assess T wave alterations with hyper- or hypokalemia.


    • Cerebral edema.



      • Most serious complication and frequent cause of death.


      • Survivors often experience neurologic sequelae.


      • Occurs in approximately 1% of cases.


      • Has been reported prior to the initiation of therapy, but typically occurs after the start of treatment.


      • Risk factors.



        • Young age.


        • New-onset diabetes.


        • Longer duration of symptoms.


      • Signs and symptoms of cerebral edema (see Section 6: Neurologic Disorders).


      • Requires rapid recognition and treatment.



        • Elevate head of bed.


        • Administer hyperosmolar therapy.



          • Preferred treatment is hypertonic saline (e.g., 3% saline).



            • 5 to 10 mL/kg.


          • Mannitol.



            • 0.5 to 1 g/kg IV.


            • May be repeated if no response.


        • Intubation and mechanical ventilation if progression of symptoms.


        • Head CT is not routinely completed prior to start of therapy, but can be obtained to evaluate and document presence of cerebral edema.


  • Respiratory support.



    • Supplemental oxygen.



      • If respiratory distress, circulatory impairment, or shock.


    • If altered mental status, consider mechanical ventilator support.


  • Access.



    • Establish multiple peripheral IV catheters.


    • May require arterial line for frequent laboratory sampling.


  • Judicious fluid replacement.



    • Avoid overaggressive fluid replacement with frequent evaluation and repeated boluses, as needed.


    • Moderate to severe DKA with poor perfusion.



      • Start with 0.9 normal saline (NS) 10 to 20 mL/kg bolus.


      • Repeat bolus if poor perfusion/hypotension persists.


      • Obtain repeat blood gas, finger-stick glucose, and basic metabolic panel after initial fluid resuscitation.


      • Remaining fluids are calculated deficits and replaced over 36 to 48 hours using isotonic fluid (e.g., 0.9 NS).



        • Subtract the volume administered in boluses from 24 hours fluid calculation.


      • Withhold potassium from fluids until evidence of adequate kidney function and serum potassium level decreasing.


      • Consider use of two-bag method when ready for introduction of glucose.



        • Allows regulation of glucose from D5W to D10W.


        • Equal electrolyte supplements are added to each bag when using two-bag method.


      • Add dextrose to IV fluids when blood glucose level is 200 to 250 mg/dL.


      • Adjust glucose to prevent rapid drop in blood glucose (e.g., >100 mg/dL/hour).


  • Insulin therapy.



    • Insulin infusion is typically started at 0.1 unit/kg/hour.


    • Follow hourly blood glucose levels.


    • Adjust the amount of dextrose in the IV fluids rather than decreasing the insulin.


    • Decrease the insulin infusion only in cases when patient demonstrates extreme sensitivity to insulin (e.g., usually young children).


    • Continue the infusion until the pH is >7.3 and bicarbonate level >18 mmol/L, or ketonemia has resolved.



  • Sodium.



    • Replace using 0.9 NS or Ringer lactate for first several hours of DKA therapy.


    • Follow this initial therapy with 0.45 NS.


    • Hyperglycemia results in a lower serum sodium concentration.



      • Results in dilutional hyponatremia, due to the movement of water into the extracellular fluid.


      • Calculation:

        Corrected Sodium = [Na+] + [1.6 × (plasma concentration mg/dL – 100)]/100


      • As hyperglycemia improves, serum sodium should improve.


      • If sodium level increases or does not begin to fall, there is concern for the development of cerebral edema.


  • Potassium.

Jan 30, 2021 | Posted by in NURSING | Comments Off on Endocrine Disorders
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