Interference with the Jaffé method for creatinine following 5-aminolevulinic acid administration.
BACKGROUND
The photosensitizer pro-drug 5-aminolevulinic acid (5-ALA) has been administered systemically for photodynamic therapy. Although several toxicities have been reported, nephrotoxicity has never been observed.


METHODS
Patients with head and neck mucosal dysplasia have been treated on a phase 1 study of escalating light doses in combination with 60mg/kg of oral 5-ALA. Serum creatinine was measured with the modified Jaffe method or an enzymatic method in the first 24h after 5-ALA. Interference by 5-ALA, as well as by its photosensitizing product protoporphyrin IX, was assessed.


RESULTS
Among 11 subjects enrolled to date, 9 of 11 had blood chemistries collected within the first 5h with 7 demonstrating significant grade 3 creatinine elevations (p=0.030). There was no additional evidence of compromised renal function or increased PDT-induced mucositis. Creatinine levels measured by the Jaffe assay increased linearly as a function of the ex vivo addition of ALA (p<0.0001). The exogenous addition of PpIX did not alter creatinine levels. ALA did not interfere with creatinine levels as measured by an enzymatic assay. A total of 4 of the 11 subjects had creatinine levels prospectively measured by both the Jaffe and the enzymatic assays. Only the Jaffe method demonstrated significant elevations as a function of time after ALA administration.


CONCLUSIONS
The transient increase in creatinine after systematic ALA can be attributed, in part, if not entirely, to interference of ALA in the Jaffe reaction. Alternative assays should be employed in situations calling for monitoring of kidney function after systemic ALA.
Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA. quon@xrt.upenn.edu
Harry
H
Quon
Craig E
CE
Grossman
Rebecca L
RL
King
Mary
M
Putt
Keri
K
Donaldson
Larry
L
Kricka
Jarod
J
Finlay
Timothy
T
Zhu
Andrea
A
Dimofte
Kelly
K
Malloy
Keith A
KA
Cengel
Theresa M
TM
Busch
D000622:Aminolevulinic Acid / Q000009:adverse effects* / Q000627:therapeutic use; D003404:Creatinine / Q000097:blood*; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000009:adverse effects* / Q000627:therapeutic use; D011446:Prospective Studies
D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid; D003404:Creatinine