Water Loading Test

Boston, MA
Best answers
I'm hoping that someone can might confirm what I'm thinking or set me straight. The patient presented for a water loading test. This is a diagnostic test where the patient drinks a specific amount of water and blood & urine tests are performed hourly over the course of 6hrs. The patient is monitored by a fellow for potential side effects. The attending would like to bill this visit on time. I've explained that there is no professional service that can be derived from this "visit". The note is listed below. I'd appreciate any helpful links/suggestions/etc to further prove my point :)...I'd also welcome any info that would even support billing a professional side E&M.

thanks in advance!

We saw Mr. XXX in our renal clinic on 6/8/12, for a water loading test to evaluate his hyponatremia and possible diagnosis of reset osmostat. he has had consistant repeated serum Na ~130 with urine osmolality that varies between 100 and 400. His last fluid intake was 12 hours prior to the test. The last time he emptied his bladder was 6 hrs prior to the test. He denied any nausea, vomiting, headache. His review of system was otherwise negative across 10-system review. His vital signs were stable and his exam was unremarkable. The plan for water intake and laboratory tests was explained to him in detail. The risks and benefits of the test was explained to him as well. All his questions were answered to his satisfaction. An informed consent was taken, after which baseline labs were sent. He was subsequently given 1700 cc (20 cc/kg) of electrolyte free water to drink over 30 min, which he drank without difficulty. He did complain of 1/10 headache after that which resolved within 15-20 min without any intevention. Serial serum sodium, serum osmolality, urine osmolality, urine sodium and urine volume were recorded. The results are listed below. He was closely monitored for any neurological symptoms every 15 min for the first hour, and then at hourly interval. The test was completed after 5 hours. Mr. XXX remained asymptomatic, his vital signs remained stable and overall, he tolerated the test well without complications.

7:30 AM
BP 121/59
wt 187.4
serum Na 128
serum osm 277
urine Na 22
urine osm 364
urine volume 240

Drank 1700 cc electrolyte free water from 8:00 to 8:30 AM

9:30 AM
BP 161/79
wt 190.2
serum Na 123
serum osm 270
urine Na 19
urine osm 329
urine vol 380

10:30 AM
BP 162/77
wt 189.8
serum Na 125
serum osm 269
urine Na 18
urine osm 232
urine vol 300

11:30 AM
BP 153/78
wt 188.8
serum Na --
serum osm --
urine Na 21
urine osm 224
urine vol 325

12:30 PM
BP 152/62
wt 188.8
serum Na 125
serum osm 274
urine Na 20
urine osm 256
urine vol 210

1:30 PM
BP 162/74
wt 188.0
serum Na --
serum osm --
urine Na 33
urine osm 281
urine vol 275

In summary, he was able to excrete 71% of his water load in 4 hours, and 88% of it in 5 hours. His serum sodium was 128 at baseline despite 12 hour fluid restriction, and was 125, 4 hours after drinking 1700 cc of free water over 30 min. He was also able to dilute his urine to a certain extent as demonstrated by a drop in urine osmolality from 364 at baseline to 256 at 4 hrs. However, with pure reset osmostat, we would have expected his urine osmolality to decrease to <100 when his serum sodium had decreased to 123. This test proves that he does have some degree of inappropriate ADH secretion. However, at the same time, this test shows that he is able to tolerate 1700 cc of free water intake over 30 min without any symptoms.This has practical implications for him. He probably would still benefit from continued fluid restriction to prevent his sodium from decreasing to a dangerously low level, however his current extent of fluid restriction is probably sufficient for him.

A total of >60 minutes was spent in face-to-face contact with Mr. XXX during this extended visit.

Dr. Fellow, MD**

On this day I was present with and reviewed today's note of Dr. Fellow for the key portion of the service provided. I agree with the findings and plan of care.

Dr. Attending, MD PhD**

**Names have been changed to protect the innocent!!