ENDO HOURDr. Marianne Joy B. Advincula

K.J.M 5/M Pampanga Chief complaint: Headache

History of present illness

2 yrs PTA- diagnosed to have craniopharyngioma with obstructive hydrocephalus

-presented with headache and nystagmus.

- S/p endoscopic guided ommaya insertion (April 2008)

- diagnosed to have central DI last June 2009, during OR, px was noted to have Na 151 and urine sg 1.000, urine volume ~1,000 cc in 3 hrs

History of present illness

6 days PTA- (+) headache, right parietal area 5 days PTA- (+) headache and vomiting -sought consult with MD, advised NSS

ff up 3 days PTA- consult done c/o NSS OPD. Vent tap

was done, no relief of symptoms Day of admission- due to persistence of

symptoms, px was brought to PGH Admission

Review of systems

(+) vomiting (-)cough (- ) colds (-) fever ( -) headache (-) LBM (-) seizure (-) changes in sensorium (+) good appetite (+) good activity

Past Medical History

(-) BA (-) PTB (-) allergies (+) previous hospitalization

› April 2008- underwent Ommaya insertion in PGH

Birth and maternal History

Born full term to a 30 yr old G3P2 (2002) mother via SVD at a local hospital assisted by an OB-Gyn

Mother had regular PNCU No feto-maternal complications No exposure to teratogenic substances No intake of abortifacient substances

Nutritional History

Breastfed at birth up to 1 year Started on complementary feeding at 6 months Presently eats regular table food

Developmental history

Creeps at 9 months Able to walk independently at 1 yr and 3 months Able to say “mama” and “papa” at 1 year old Speaks in sentences at 2 yrs old

Immunization History

Completed Epi

Personal social history

Third of 4 children, mother is 35 yrs old while father is a 38 yr old jeepney driver

Physical examination on admission

Conscious, coherent, not in distress BP- 100/60 CR- 84/min RR- 20 T- 37.1°C Wt: 19 kg Ht- 110 cm HC- 52 cm Anicteric sclerae, pink conjunctivae, (+) good shunt

rebound SCE, no retractions, CBS AP, normal rate and regular rhythm, no murmurs Abdomen flat, soft, normoactive bowel sound, no

masses Full and equal pulses, no edema, no cyanosis

Neurologic exam

GCS-15 Pupils 2 mm ERTL Intact EOMs (-) facial asymmetry (+) intact gross hearing (+) gag (+) tongue midline

MMT- gr 5/5 all extremities Sensory- intact (+) Babinski

Admitting Impression

Suprasellar mass secondary to craniopharyngioma with obstructive hydrocephalus

S/P endoscopic guided ommaya shunt insertion- 4/2008

Hypothyroidism, Hypocortisolism Central DI, resolved

COURSE AT THE WARD

Upon admission, baseline serum electrolytes showed Na 134, K 3.6, Cl 96, Ca 2.51. Baseline urinalysis showed light yellow/ clear/ 1.010/ 7.0/ neg sugar and alb/ RBC 4/ WBC 1.

On the 1st HD- 24 hr urine output was 4,150 ml. Serum and urine electrolytes were done, showing Na 146/ K 4/ Cl 112. Urine electrolytes showed Na 36/ K 4.9/ Cl 37. Plan was to do water deprivation test. Urine losses were replaced in excess of 3 cc/kg/hr with OFI

3rd HD- Na was noted to be 146, minirin 0.1 mg/tab, ½ tab was given as stat dose

UO- 770 ml after minirin

8th HD- minirin started 0.1 mg/tab, ½ tab at bedtime

9th HD- Na 128, K 3.5, Cl 94, NaCl tabs started, 1 tab q 3 hrs

Urine Na 33/ K 8.3/ Cl 26 Serum Na 135/ K 4.0/ Cl 102 Minirin put on hold

Case Discussion

Diabetes Insipidus

Presents with polyuria and polydipsia

central DI- result from vasopressin deficiency nephrogenic DI- vasopressin insensitivity at the

level of the kidney

Central diabetes insipidus

Etiologies: 1. genetic mutations in the vasopressin gene 2. trauma (accidental or surgical) to vasopressin

neurons› triphasic response – after surgery, refers to an initial

phase of transient DI, lasting 12–48 hr, followed by a 2nd phase of syndrome of inappropriate antidiuretic hormone secretion, lasting up to 10 days, which may be followed by permanent DI

3. congenital malformations of the hypothalamus or pituitary

4. neoplasms- tumors that cause DI must either be very large and infiltrative or be strategically located near the base of the hypothalamus, where vasopressin axons converge before their entry into the posterior pituitary

5. infiltrative 6. autoimmune 7. infectious diseases affecting vasopressin neurons

or fiber tracts 8. increased metabolism of vasopressin

Symptoms

The major symptoms of central DI are polyuria and polydipsia.

Polyuria is defined as a urine output of over 3 L/day in adults. The onset of polyuria is usually abrupt in CDI. This is in contrast to nephrogenic DI and primary polydipsia,

in which onset of polyuria is almost always gradual.

Symptoms

Nocturia is often the first sign of CDI. This is because urine is usually most concentrated in

the morning due to lack of fluid ingestion overnight. As a result, nocturia is usually the first manifestation

of a loss of concentrating ability. Thus, a relatively dilute urine is excreted, with a

urine osmolality of less than 200 mOsmol/kg. Dry skin and constipation are other symptoms that

may occur in CDI.

Diagnostics

serum for osmolality, sodium, potassium, blood urea nitrogen, creatinine, glucose, and calcium; urine for osmolality, specific gravity, and glucose determination.

The diagnosis of DI is established if the serum osmolality is greater than 300 mOsm/kg and the urine osmolality is less than 300 mOsm/kg.

DI is unlikely if the serum osmolality is less than 270 mOsm/kg or the urine osmolality is greater than 600 mOsm/kg

If serum osmolality is less than 300 mOsm/kg (but greater than 270 mOsm/kg) and pathologic polyuria and polydipsia are present, a water deprivation test is indicated to establish the diagnosis of DI and to differentiate central from nephrogenic causes.

Water Restriction Test

In healthy individuals, water deprivation increases plasma osmolality, which stimulates secretion of ADH by the posterior pituitary.

This then acts on the kidney to increase urine osmolality to 1000 to 1200 mOmol/kg and to restore plasma osmolality to normal levels.

Giving exogenous ADH does not increase urine osmolality further because it is already maximal in response to an individual’s endogenous release of ADH.

Water Restriction Test

Method:› Water restriction lasts 4 to 18 hours.› Overnight fluid restriction should be avoided, as

severe volume depletion and hypernatremia can be induced in patients with severe polyuria.

› Measure the urine volume and osmolality every hour and serum sodium concentration and osmolality every two hours.

Water Restriction Test

The test should be continued until one of the following occurs:› The urine osmolality reaches a normal value, which is above 600

mOsm/kg, indicating that both ADH release and effect are intact. › The urine osmolality is stable on 2 or 3 successive measurements

despite a rising plasma osmolality.› The plasma osmolality exceeds 295 to 300 mOsm/kg.› In the last two settings, the serum ADH level is measured, which is

also performed at the start of the test, and then exogenous ADH is administered (10 microgm of dDAVP nasally or 4 microgm sq).

› Urine osmolality is then measured every 30 minutes for the next 3 hours.

Water Restriction Tests

Interpretation:› Normal subjects and primary polydipsia:

Urine osms are greater than plasma Osms after water restriction. Urine osms increase minimally (<10%) after exogenous ADH.

› Central Diabetes Insipidus: Urine osms remain less than plasma osms after water restriction. After ADH is given, urine osms increase 100% in complete CDI and

over 50% in partial CDI.› Nephrogenic Diabetes Insipidus:

Urine osms remain less than plasma osms. After ADH, urine osms increase by less than 50%.

Treatment

Treatment is primarily aimed at decreasing the urine output, usually by increasing the activity of ADH.

Replacement of previous and ongoing fluid losses is also important, either with oral water intake or IVF such as D5W if the patient is unable to take fluids by mouth.

There are several medications available for the treatment of CDI, of which desmopressin is the most common.

Desmopressin

Desmopressin is a two-amino acid substitute of ADH that has potent antidiuretic activity but no vasopressor activity.

It is also known as dDAVP, which stands for 1-deamino-8-D-arginine vasopressin.

It is currently the drug of choice for long-term therapy of CDI to control polyuria.

It is safe during pregnancy for both the mother and the fetus.

Risks of Desmopressin

Potential risks of desmopressin include water retention and the development of hyponatremia.

This may occur because once dDAVP is given, the patient has nonsuppressible ADH activity and may be unable to excrete ingested water normally.

This can be avoided by giving the minimum daily dose required to control the polyuria.

Other Drugs

For the vast majority of patients with CDI, dDAVP is readily available, safe, and effective.

Therefore, it is rarely necessary to add other drugs to the regimen.

The other agents available are less effective and associated with more adverse effects than desmopressin.

Chlorpropamide, carbamazepine, and clofibrate can be used in cases of partial CDI and can lower the urine output by as much as 50%.

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Serum elestrolytes

Na 134 146 136 134 128 125 134 135 137 148 136

K 3.6 4.0 4.3 3.7 3.5 3.8 3.9 4.0 4.3 3.4 3.8

Cl 96 112 99 100 94 90 103 102 103 115 99

Urine electrolytes

Na 20 36 33 19 26 75 36

K 6.4 4.9 8.3 4.3 17.5 4.7 11

Cl 22 37 26 24 41 75 24

USG 1.015

1.004

1.027

1.002

1.005

1.006

1.003

INPUT/OUTPUT

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Input 4076 4250 1235 2550 4685 3630 3965 2465 3463 5175

Output

2880 3060 1210 3110 4030 3420 3980 2380 4280 5900