Is this SIADH ?

[ghost dog]

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Saw a pt recently, and wondering if people could weigh in here.

19 year old lady, recently started on Celexa for MDE; taking x 2 months and now on
40 mg OD. Moderate response. She weighs approx 240 lbs.

2 weeks ago, she had a 3 day episode of nausea / vomiting and diarrhea which resolved. However, she has persisting anorexia. Her grandmother is concerned about this, as the patient has not been eating, and is drinking less fluids for the past 2 weeks.

O/E: HR = 119 reg BP = 135 / 80 sitting.

HR = 135 reg BP = 115 / 60 supine

Na+ = 127

Considering both the hyponatremia, and orthostatic drop , I sent her to the ER with the appropriate documentation ( including the fact that she was taking Celexa).

Do you think this is SIADH, or simple dehydration ?

 

[DD214_DOC]

Saw a pt recently, and wondering if people could weigh in here.

19 year old lady, recently started on Celexa for MDE; taking x 2 months and now on
40 mg OD. Moderate response. She weighs approx 240 lbs.

2 weeks ago, she had a 3 day episode of nausea / vomiting and diarrhea which resolved. However, she has persisting anorexia. Her grandmother is concerned about this, as the patient has not been eating, and is drinking less fluids for the past 2 weeks.

O/E: HR = 119 reg BP = 135 / 80 sitting.

HR = 135 reg BP = 115 / 60 supine

Na+ = 127

Considering both the hyponatremia, and orthostatic drop , I sent her to the ER with the appropriate documentation ( including the fact that she was taking Celexa).

Do you think this is SIADH, or simple dehydration ?

Wouldn't dehydration cause hypernatremia? The HR and BP suggests volume depletion, but typically you would see a rise in serum Na+, although you can lose Na+ through diarrhea I think.

 

[michaelrack]

Wouldn't dehydration cause hypernatremia? .

unless you lose more salt than free fluids

 

[michaelrack]

O/E: HR = 119 reg BP = 135 / 80 sitting.

HR = 135 reg BP = 115 / 60 supine

?

maybe I am reading this wrong, but it looks like the bp dropped (and HR rose) when lying down. That's the opposite of orthostasis.

Were any urine studies done (NA, osmolality)?

 

[heyjack70]

I vote for hypovolemic hyponatremia as most likely. Depends on clinical exam of course, if patient appears hypovolemic, no axillary sweat etc. If the patient hasn't been eating or drinking it's likely she is dehydrated.

In Response to Hooah Doc: You can get hyponatremia with dehydration as well. With dehydration, the circulating volume goes down, so the RAAS is activated, trading K+ into the kidney tubule for Na+ and water back into the circulation attempting to return to euvolemia. Once the RAAS is maxed out, ADH continues the effort to return to euvolemia, leading to free water resorption from the collecting duct (aquaporin 2 channels), but this water is resorbed without any Na+ leading to a relative hyponatremia in the circulation. So I think this is a syndrome of "appropriate" ADH secretion in a dehydrated pt.

There is a more intense workup for hyponatremia involving Urine osm/Na+ and calculating fractional excretion of Na+ which may prove me wrong, meaning SIADH is still possible, but based on the limited clinical history it sounds like SIADH is the Zebra.

 

[splik]

NO. If the patient is hypovolemic as is suggested by description of fluid status SIADH cannot be diagnosed. In SIADH the patient must be euvolemic.

Paired serum/urine osmolalities are often done in these cases but in reality they are fairly useless and don't really tell you anything a good clinical exam wouldn't.

Any weight loss? pigmentation? hypoglycemia? Addison's is on the differential here, but it could be due to simple dehydration if the nausea/vomiting came first. Is there a possibility of surreptitious diuretic use?

 

[ghost dog]

maybe I am reading this wrong, but it looks like the bp dropped (and HR rose) when lying down. That's the opposite of orthostasis.

Were any urine studies done (NA, osmolality)?

You're right, I made a mistake - the supine should read standing. My bad.

 

[ghost dog]

NO. If the patient is hypovolemic as is suggested by description of fluid status SIADH cannot be diagnosed. In SIADH the patient must be euvolemic.

Paired serum/urine osmolalities are often done in these cases but in reality they are fairly useless and don't really tell you anything a good clinical exam wouldn't.

Any weight loss? pigmentation? hypoglycemia? Addison's is on the differential here, but it could be due to simple dehydration if the nausea/vomiting came first. Is there a possibility of surreptitious diuretic use?

These are really good thoughts:

1. Possibly hyperpigmented, although she has a mother who is dark skinned hard to say. No change in pigmentation since I have known her through, and no hx of change in pigmentation per grandmother.

2. The diuretic angle is certainly an interesting thought.

I question the simple dehydration, as the episode of ? gastro had only lasted 3 days and then resolved 2 weeks ago. This is the primary reason why I wondered if the SSRI Celexa was playing a role here. She denied orthostatic sxs.


I will keep you updated when I get the ER / consult note.

 

[ghost dog]

These are really good thoughts:

1. Possibly hyperpigmented, although she has a mother who is dark skinned hard to say. No change in pigmentation since I have known her through, and no hx of change in pigmentation per grandmother.

2. The diuretic angle is certainly an interesting thought.

I question the simple dehydration, as the episode of ? gastro had only lasted 3 days and then resolved 2 weeks ago. This is the primary reason why I wondered if the SSRI Celexa was playing a role here. She denied orthostatic sxs.


I will keep you updated when I get the ER / consult note.

Pt had a ruptured appendix - truly bizarre. She did not complain of abdo pain.

 

[heyjack70]

I'm glad you sent her to the hospital.

 

[firedoor]

Do you think this is SIADH, or simple dehydration ?

What was the vasopressin level?


















/

 

[ghost dog]

What was the vasopressin level?


I didn't order this, and I don't believe this was ordered at the hospital - the patient had a ruptured appendix.

This 19 year old lady received a radiologically guided drainage of an abdominal abscess, and was discharged 3 days later. She did very well - thankfully.

I think this shows that we ( as doctors and diagnosticians) can get tunnel vision, when a certain diagnosis is fixated upon. In particular, I queried SIADH due to the patient's Celexa and hyponatremia, and let other diagnoses fall by the wayside. This particular pt presented in a somewhat atypical manner in regards to her ruptured appendix (i.e. no abdo pain).

I should note that she did have a WBC count of 30, which I missed due to my tunnel vision. In my defense, the lab results were presented in a bit of an awkward manner ( although this is certainly no excuse).

I'm very glad I sent her to the ER.