An 86 year old with CKD

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An 86 year old woman who is resident in a local nursing home is known to have stage 3 CKD, hypertension, peripheral vascular disease, eczema, osteoporosis, and moderate Alzheimer’s disease. She is usually independent in dressing and eating and drinking. In the past, urinary tract infections have been associated with worsening in her cognitive state.

Usual medications:  Bendroflumethiazide, Perindopril, Donepezil, Omeprazole, Alendronate (weekly), Calcichew-D3.

She was seen as a home visit 5 days ago due to increased confusion and reduced oral intake.  She appeared clinically dehydrated, pyrexial (38.2°C) and BP was 100/55.  Urine dipstick showed ++Blood, +Protein, +Nitrites, +Leukocytes.  An MSU was taken and she was started empirically on Trimethoprim.

U&Es taken at the time were available later that evening and showed worsened renal function (see below), at which point the nursing home was phoned and the thiazide diuretic and ACE inhibitor stopped.  She was reviewed this morning, and she was now apyrexial, her cognitive state was improved, and the nursing staff reported that her oral intake was now starting increase.  However despite this reported improvement, her renal function had deteriorated further.

Serial Blood tests     Urea  (mmol/L)  Creatinine(umol/L) Sodium            Potassium

GP 5 months ago             8.7                        133umol/L              136                        4.5
Initial consult                  20.6                        205umol/L              151                        5.4
Today                             22.3                        267umol/L              147                        5.7

Neither the GP nor the patients family were keen on admission to hospital, as that had been associated with worsened confusion and agitation in the past, but they wonder if this is now necessary?

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Now read what the expert wrote

This lady has acute kidney injury on a background of chronic kidney disease.UTI can cause renal dysfunction in its own right, particularly in the elderly and those with pre-existing CKD.  In this case the history and the elevation of serum sodium, urea and creatinine in the first set of U&Es suggests that the patient is significantly dehydrated.  It is unusual to see overt hypernatraemia unless something – in this case possibly reduced cognition – prevents the patient from drinking in response to thirst.

Stopping the ACEi and thiazide was appropriate.

The use of trimethoprim will partially confound the interpretation of the second set of U&Es, as it competitively inhibits renal tubular creatinine secretion, causing increases in serum creatinine of around 30% in patients with CKD, which could partially or fully account for the apparent worsening in her lab results.

The potassium level does not mandate admission, and whilst there has been an improvement in the sodium level, there is still a water deficit and probable dehydration present.  My advice is not to admit to hospital, but to push oral fluids in the nursing home, repeating bloods at the end of the week once the course of trimethoprim had been discontinued. This should be safely managed in the community as long as function does not continue to decline.

Last Updated on February 2, 2025 by admin