NHD digital edition - issue 37 August 2008

case study: clinical chemistry
An extract from
by Dr Fred Pender Clinical Cases in
Dietitian and Author
Dietetics
Stroke, clinical chemistry blood tests you would request prior
This will be
Study concepts: dietary intervention to feeding.
quickly
post-stroke, clinical chemistry as a basis (5) Discuss the nutritional care plan for
corrected on administra-
for feeding, management of a client this client and relate this to Ques-
tion of intra-venous ﬂ uids. CRP and
using nasogastric feeding, re-feeding tion 3.
albumin levels are normal, indicat-
syndrome (6) Calculate the patient’s ﬂ uid and
ing that there is no underlying infec-
tion. Interpretation of these results
Study context: stroke, clinical chemistry
electrolyte requirements (calcium,
would be assisted by ﬂ uid balance
Maude Ashby lives on her own and
sodium, magnesium, phosphate
information and clinical observation
remains ﬁ ercely independent de-
and potassium).
of skin turgor.
spite her years (80 years of age). She
(7) Using a standard feed, design a
• Some blood tests would assist in
returned from a recent trip to the local
possible feeding regimen.
determining the feeding regimen,
shops to collect her pension and do Study questions
including plasma/serum urea, elec-
a bit of grocery shopping and shortly (1) Explain the possible causes of de-
trolytes, magnesium, phosphorus
after this collapsed on her kitchen ﬂ oor. hydration in an older, but free-living
and corrected calcium (re-feeding
Her daughter visited her the following individual.
syndrome may be likely now that
morning and called 999 to get help. (2) Describe the possible bedside ob-
the patient has been ﬁ ve days nil-
Mrs Ashby was immediately transported servations that may assist in classify-
by-mouth). |Levels of these nutrients
to the local district hospital. It was esti- ing an individual as dehydrated.
need to be corrected as required.
mated that she had been unconscious (3) Explain the possible inﬂ uence of de-
• The regimen needs to be construct-
for about 16 hours. She has a stable hydration when interpreting clinical
ed to meet nutritional requirements.
weight (62 kg, height 160 cm) chemistry results.
Fluid balance needs to be moni-
On admission, the consultant (4) Explain the phenomenon known as
tored to identify under/over hydra-
diagnosed a stroke and routine blood ‘re-feeding syndrome’, and discuss
tion and allow amendment in the
investigations were done and repeated how this can be avoided in clinical
ﬂ uid provided. Monitoring of urine
(24-hr post-admission). The results are practice.
and blood electrolytes, serum/plas-
given below. She remains on intrave-
nous ﬂ uids for four days, and following
Commentary
ma magnesium, corrected calcium
the unsafe swallow assessment by the
• Initial impressions of the case sug-
and phosphorus should continue
SLT, the decision is made to feed using
gest that the patient is normally ﬁ t
after feeding and then two to three
a nasogastric feed.
and well with a presumed good
times a week or more frequently
food intake. This view is supported
if levels are abnormal and requir-
Questions to consider by a normal-to-healthy BMI (24kg/
ing correction. Abdominal func-
(1) Taking each constituent in turn, m_). However the patient has been
tion should be monitored (nausea,
comment on the patient’s clinical left for >72 hr prior to feeding which
vomiting and bowel movement).
chemistry results on admission. is not in accordance with national
There is a need to conﬁ rm the posi-
(2) Comment fully on the patient’s guidelines for management of
tion of the nasogastric tube with pH
clinical chemistry on admission + stroke victims.
indicator paper (and a pH <5.5 prior
day 1 and explain the changes. • Baseline assessment: all serum levels
to use of tube).
(3) In addition to blood tests, what are within normal ranges on admis-
• Requirements should be calcu-
other clinical information might be sion, but all at the higher end of
lated using predictive equations.
useful to assist with interpretation of normal. This is likely to reﬂ ect some
Energy: BMR = (9.8 X 62) + 624 =
the results? underlying dehydration caused by
1232kcal, addition of a stress factor
(4) The patient is to start nasogastric the patient being without ﬂ uids for
= +5% (62kcal) = 1294kcal, and the
feeding. Indicate and explain the up to 16 hours prior to admission.
addition of activity factor = +15%
(185kcal) = 1479kcal/d. Protein =
Serum/plasma con- Result (on ad- Result (at 1 day Reference
0.17 x 62 = 10.54gN = 66g protein/d.
stituent mission) post-admission) range
Fluid requirement = 30 x 62 = 1860ml.
Albumin (g/l) 45 41 35–45
• An appropriate feeding regimen
may be:
Calcium (mmol/l) 2.5 2.5 2.25–2.65
ß Day 1: Jevity 50ml/hr x 20hr, con-
C-reactive protein (mg/l) 7 7 <10
tinue with 24hr intravenous ﬂ uids (i.e.
Calcium (mmol/l) 136 136 40–130
1000ml) (=1000kcal, 40g protein,
2000ml).
Haemoglobin (g/dl) 13.1 12.5 11.5–15.5 (female)
ß Day 2: Jevity 75ml/hr x 20hr, water
Magnesium (mmol/l) 0.7 0.8 0.7–1.0 100ml/hr x 4hr (=1500kcal, 60g pro-
Potassium (mmol/l) 4.9 4.1 3.5–5.0
tein, 1900ml).
ß Day 3: Jevity 100ml/hr x 15hr,
Phosphate (mmol/l) 1.4 0.9 0.8–1.4
water 150ml/hr x 2hr (=1500kcal, 60g
Total protein (g/l) 72 69 60–80 protein, 1500ml).
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