friday afternoon brain freeze

Re: friday afternoon brain freeze

Kate Richardson — Sat, 03 Nov 2012 05:04:14 GMT

Yes USG can be lowered with hyperthyroidism but in my experience a USG as low as this suggests renal insufficiency. Urea can be difficult to interpret in hyperthyroid cats as it is often mildly elevated even with out concurrent RI and creatinine is more sensitive with respect to renal disease- agree to check IRIS values- creat 147 with USG 1.014- RI gets my vote. How long has cat been on treatment for? If you are not getting the weight gain you would expect for a straightforward hyperthyroid, then that also adds weight to cat having concurrent RI. Yes I would check UPCR and I would also make sure you check BP. I would definitely start renal diets and monitor BP/urine incl C&S and UPC/potassium/phos levels regularly as well as your usual T4/urea/creat, but most importantly don't forget to listen to the cat- if it is stable at these blood figures then don't make changes for changes sake. T4 at that level with concurrent CRI I would be more than happy with

Re: friday afternoon brain freeze

Rajat — Fri, 02 Nov 2012 17:23:34 GMT

[quote user="Robin Grimmer"]I don't think measuring GFR is something you can readily do in the practice environment.[/quote]

Actually you can, quite easily, if you can take a blood sample... see the link I posted.

However, early renal profile is even easier. Just need blood and urine taken more or less at the same tim. They aren't the same test by any means, but help to further evaluate the disease.

You are right one has to avoid hypothyroidism while treating these kitties.

Another thought re diet- a senior high calorie diet eg royal canin senior stage 2 high cal in a non azotemic kitty may be beneficial for a while if she was markedly catabolic from thyroid disease.

Re: friday afternoon brain freeze

Robin Grimmer — Fri, 02 Nov 2012 17:12:22 GMT

I don't think measuring GFR is something you can readily do in the practice environment. Having watched the Danielle Gunn-Moore CPD on hyperthryoidism (which is free and on the Dechra website) - the main thing to avoid is iatrogenic hypothryoidism. This has been associated with worsening of the kidney disease and poorer survival times. So I think your T4 level is fine, I would just recommend starting on a renal diet :)

Re: friday afternoon brain freeze

Simon Neuhoff — Fri, 02 Nov 2012 17:00:25 GMT

My understanding of it - following an excellent CPD evening with martha cannon - was that hyperthyroidism can reduce usg - but only mildly. In this case I would be suspicious of concurrent renal disease - it seems suspiciously low for hypert4 only.

Re: friday afternoon brain freeze

Simon Neuhoff — Fri, 02 Nov 2012 17:00:25 GMT

Re: friday afternoon brain freeze

Rajat — Fri, 02 Nov 2012 16:57:50 GMT

[quote user="Hannah Bose"]

[quote user="Rajat"]I suppose an advanced test to check GFR may be feasible. Or checking early renal profiles to check fractional excretion of solutes- blood and urine taken at same time - send to lab (we use axiom) for this.[/quote]

I have not heard of such things commercially available. Do you find them useful? What do they tell you exactly?

[/quote]

The GFR test (eg iohexol clearance test) - in PUPD cats and dogs they tell you if GFR is wnl or reduced. Allows you to differentiate renal vs non renal cause of PUPD where there is no azotemia. Also helpful to track GFR changes in certain patient populations. the iohexol clearance test does need to go to michigan but is quite simple to do.

An early renal profile (at axiom) - it allows you to see what the fractional excretion of solutes is as well as assesing urine nag:creat ratio which assesses tubular damage..it includes a UPC to pick up on glomerular dzs too. I find the ERP very useful. GFR tests can be straightforward or involved dependign on what you choose but you have to pick the case properly. May not be appropriate in an uncontrolled hyperthyroid case I appreciate this is not your situation).I would do imaging first (ultrasound)- if changes consistent with renal disease then that gives you further pointers as to cause of clinical signs before doing a GFR test in your kitty.

You may find this informative.- http://veterinarymedicine.dvm360.com/vetmed/Medicine/Practical-ways-to-measure-GFR-in-your-patients/ArticleStandard/Article/detail/703813

cheers

Rajat

Re: friday afternoon brain freeze

HMC — Fri, 02 Nov 2012 16:57:46 GMT

[quote user="Rajat"]How about phosphate levels? What are they like?[/quote]

Annoyingly I sent to Idexx for the thyroid monitoring profile, which does not include phosphate. I think I'm going to send everything for the 'wellness' screen from now on as I am fed up of finding phosphate is not included (for example in the old thin cat profile!?).

Re: friday afternoon brain freeze

Rajat — Fri, 02 Nov 2012 16:49:14 GMT

Depends on your labs reference range. Mine is 15-40. If yours goes upto 60 (40-60 is considered equivocal by some labs) then 36 may well be appropriate. The recommendation while tx hyperT is to have it in the lower half of the reference range.

But (stating the obvious, sorry) one has to do it in conjunction with clinical signs and improvements on said doses...

So, using my lab's reference ranges, if I had a hyperT cat who after tx gained alot of weight and his T4 was in the thirties I would be ok with it (with close monitoring.)

Re: friday afternoon brain freeze

HMC — Fri, 02 Nov 2012 16:47:33 GMT

I have not heard of such things commercially available. Do you find them useful? What do they tell you exactly?

Re: friday afternoon brain freeze

Rajat — Fri, 02 Nov 2012 16:45:51 GMT

[quote user="James Laidlaw"]Wouldn't hurt to start renal diets. Any protein on dipstick? I'd say a USG of 1.014 with uraemia has to mean there is renal involvement here, there was a good article on CKD in last weeks vet times too.

[/quote]

If creatinine was elevated I would be more convinced. Equally, it depends on amount of muscling on cat because this creat in a cat with a BCS of 2/9 is high.

IRIS use lower creatinine levels btw than many labs ( Ithink 140-150 if memory serves)

I don't think a spot check of urea at this mild elevation along with USG of 1.014 is conclusive by any means for intrinsic loss of renal concentrating ability. A meal with a decent amount of protein a few hours ago could push the urea up above the reference range.

Also, worth remembering, some cats can maintain concentration when we remove the vast majority of their renal mass.

So basically they like to confuse us.

But, the query being, can hyperthyroidism cause a low USG (independent of renal status or in the face of normal renal concentrating ability) - the answer is yes. Yes, renal disease (whether manifested as loss of concentrating ability or azotemia) is often masked by hyperthyroidism which when treated results in renal blood flow reductions and hence unmasking of the renal dzs - in this case, under treatment (one assumes, as T4 is just below top end of reference range/at high end of reference range depending on yr lab) there has been no overt azotemia.

If this was a fasted blood sample, I would pay a little more attention to the urea. Otherwise I'd mainly concntrate on creatinine in terms of tracking renal function (keeping in mind muscle mass too tho).

How about phosphate levels? What are they like?

Re: friday afternoon brain freeze

HMC — Fri, 02 Nov 2012 16:45:48 GMT

[quote user="James Laidlaw"]Wouldn't hurt to start renal diets.[/quote] That's the philosophy I might use in this case.... but we'll see what the owner wants.

Re: friday afternoon brain freeze

HMC — Fri, 02 Nov 2012 16:44:04 GMT

[quote user="Rajat"]Would be interesting to see what happens to USG when TT4 is a bit lower.[/quote]

Why would you try to get it lower than 36?

Re: friday afternoon brain freeze

HMC — Fri, 02 Nov 2012 16:43:12 GMT

[quote user="Robin Grimmer"]What is the history [/quote]

On 5mg felimazole morning and 2.5mg evening. Has had renal parameters tested previously and once had high urea/creatinine but the last two readings (incl this one) are much more normal. She had not been starved prior to this most recent sample. Has had consistently low usg. BP 130mmHg.

[quote user="Robin Grimmer"]clinical signs[/quote]

Doing well. Not pupd as far as the owner can tell... Weight stable at 3kg.

Re: friday afternoon brain freeze

Robin Grimmer — Fri, 02 Nov 2012 16:24:57 GMT

agree with the above. Probably has got early/mild kidney disease. What is the history and clinical signs? Any weight loss, pupd, palpable goitre etc.?

Re: friday afternoon brain freeze

James Laidlaw — Fri, 02 Nov 2012 15:49:25 GMT

Wouldn't hurt to start renal diets. Any protein on dipstick? I'd say a USG of 1.014 with uraemia has to mean there is renal involvement here, there was a good article on CKD in last weeks vet times too.

Re: friday afternoon brain freeze

Dagmar Steele — Fri, 02 Nov 2012 15:39:38 GMT

many hyperT4 cats suffer from renal failure, too. It may but well be masked by high blood pressure created by hyperT4, hence if the T4 comes down renal values may rise. I wouldn't expect low usg be caused by hyperT4 but rather by renal issues, hard to tell beforehand though. If you can check GFR surely a good idea, otherwise try to bring T4 down very gentle and monitor closely what happens to renal values. If they rise you're caught between a rock and a hard place :-( Good luck!

Re: friday afternoon brain freeze

Rajat — Fri, 02 Nov 2012 15:31:15 GMT

[quote user="Hannah Bose"]Could the low usg be caused by hyperthyroidism[/quote]

Yup it could be. There's various theories as to causes.

Tough to tell whether there is concurrent renal dzs. UPCR and culture always worth doing int hese kitties with reduced USGs and renal +/-thyroid

I suppose an advanced test to check GFR may be feasible. Or checking early renal profiles to check fractional excretion of solutes- blood and urine taken at same time - send to lab (we use axiom) for this.

Would be interesting to see what happens to USG when TT4 is a bit lower.

Cheers

Rajat