Gilhooly, C.J.

Kinsella, J.

Mackie, S.

O'Reilly, D.

Shaw, M.

English

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Gilhooly, C.J. and Mackie, S. and O'Reilly, D. and Shaw, M. and 
Kinsella, J. (2009) The incidence, severity, timing and circadian variation 
of hypophosphataemia in Glasgow Royal Infirmary Intensive Care Unit 
[poster]. In: Scottish Intensive Care Society Annual Scientific Meeting, 
22-23 Jan 2009, Cumbernauld, UK. (Unpublished) 
 
http://eprints.gla.ac.uk/5391/ 
 
Deposited on: 06 April 2010 
 
 
Enlighten – Research publications by members of the University of Glasgow 
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Aims
Methods
A retrospective audit of data entered in computerised 
medical record database (CareVue) from of al l 
admissions between 27/04/2006 (when the electronic 
record was initiated) and 07/07/2008. The time, date 
and value of all serum phosphate concentrations were 
analysed. The phosphate concentrations of all patients 
were then analysed by time of day of sampling and day 
after admission. Abnormal phosphate concentrations in 
mmol/l were subsequently categorised as the following: 
critically low (< 0.3), low  (<0.7), high (>1.5). 
CJ Gilhooly*, S Mackie*,M. Shaw*, D O’Reilly†, J Kinsella*
*Section of Anaesthesia, Pain & Critical Care Medicine, Division of Developmental Medicine, Faculty of Medicine - University of Glasgow, 
Level 2, QEB, Glasgow Royal Infirmary,10 Alexandra Parade, Glasgow  G31 2ER
†Glasgow Royal Infirmary, 84 Castle St, Glasgow, G4 0SF
Hypophosphataemia is a common treatable problem in 
the Intensive Care Unit (ICU), and can be indicative of 
many pathophysiological processes that occur in critical 
illness. Many processes that occur in critical illness will 
have an effect on phosphate concentrations in ICU 
admissions.  In normal patients there is a well defined 
circadian effect on phosphate concentrations that is 
secondary to the Parathyroid hormone axis1. 
The incidence, severity,  timing and circadian 
variation of hypophosphataemia in Glasgow 
Royal Infirmary Intensive Care Unit
Results:
References
1. Fraser, WD et al.: Clinical Endocrinology 1994; 40: 523-528
Background
The objectives of this audit were to quantify the 
incidence, severity and timing of hypophosphataemia in 
Glasgow Royal Infirmary Intensive Care Unit.  Namely 
the incidence of hypophosphataemia on admission to 
ICU and the incidence of hypophosphataemia that 
develops following admission. In addition, we aimed to 
examine  the effect of timing of blood samples and see 
if this could potentially influence the diagnosis of 
hypophosphataemia. 
Results
Results
689 of 795 patients admitted during this period had a 
serum phosphate recorded.  The table below shows 
that the incidence of hypophosphataemia on admission 
to GRI ICU is 10% of which less than 1% is at a critical 
concentration. However, the incidence of 
hypophosphataemia during the whole of the ICU stay 
rises to 42% of admissions.  5% of ICU admissions get 
critical hypophosphataemia at some point during their 
ICU stay.  69% of these patients have a normal or high 
concentration of phosphate on admission, 19% have a 
low admission phosphate and 13% are admitted with a 
critically low phosphate concentration. 
Conclusion
Phosphate Level Admission
N (%)
Minimum (at any time)
N (%)
All 689 689
Critically low 4 (0.4%) 32 (5%)
Low 69 (10%) 289 (42%)
Normal 364 (53%) 311 (45%)
High 256 (37%) 89 (13%)
A total of 10,987 samples were analysed. Frequency 
(Fourier) analysis on all data showed two peaks.  The 
predominant (fundamental frequency) showed a periodicity 
of 25 hours, a second lesser fundamental frequency showed 
a periodicity of 2.5 hours.
Figure: Diurnal variation of phosphate concentrations
Figure: Smoothed periodogram of phosphate concentration
Hypophosphatemia is common in ICU admissions.  Most 
commonly it develops subsequent to admission to ICU and 
reaches critical levels in 5% of ICU admissions.  The timing 
of this fall in phosphate may indicate specific 
pathophysiological processes and merits further 
investigation. There continues to be a circadian variation in 
phosphate concentrations in ICU.  This shows different 
characteristics to the normal rhythms but sample time can 
still influence phosphate concentrations, and subsequent 
diagnosis of abnormal phosphate concentrations. 
SICS January 2009


The incidence, severity, timing and circadian variation of hypophosphataemia in Glasgow Royal Infirmary Intensive Care Unit [poster]

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