Hyperthyroidism Associated with Periodic Paralysis and Hypopotassaemia
Authors: N. Anderssen, K. Wigmostad
Journal: BMJ (1959)

BxJr 1389of chloroquine and a much lower dosage.The number of cases is too small to draw any firm conclusions, but the remarkable similarity in the features suggests the possibility that it is the duration of treatment with chloroquine and not the dosage employed that is responsible for this toxic reaction.However, in Case 2 restoration of normal hair-colouring occurred when the dosage was reduced to a minimum, although this was not effective in Case 1.This would suggest that duration of treatment is not the only factor concerned.In both Cases 1 and 3 normal colouring has returned since changing from chloroquine diphosphate to hydroxychloroquine sulphate.The first two patients also complained of severe erythema of the skin on exposure to sunlight.This did not arise in the third patient, who has disseminated lupus erythematosus and had been specifically warned to avoid bright sunlight.The patient treated by Sharvill made a similar complaint.This observation is of particular interest, as chloroquine is an accepted form of treatment for actinic dermatitis.Sharvill noticed that his patient's hair gave a bluishwhite fluorescence similar to that of a suspension of chloroquine sulphate when viewed with Wood's lamp.This we have been able to confirm in the affected parts of the hair in our cases, using a suspension of chloroquine diphosphate for comparison.The part of the hair grown since changing to hydroxychloroquine sulphate did not fluoresce.Although not confirmed by chemical analysis, this finding suggests that the "bleached" appearance is due to the deposition of chloroquine in the hair instead of the natural pigment.The fact that freckles did not appear and the skin did not tan normally with sunlight suggests that, in the skin also, chloroquine may replace the natural pigment, or at least interfere with the deposition of pigment.It would appear that in the hair these changes are reversible.'Further observation during the summer months is required to see whether or not the skin will tan normally.Three preparations of chloroquine have been men- tioned: chloroquine sulphate, chloroquine diphosphate, and hydroxychloroquine sulphate.All three are in current use for the treatment of rheumatoid arthritis.Pigmentary disturbance has been recorded by Sharvill usingi the sulphate preparation ("nivaquine '), and in this paper when using the diphosphate salt.From our limited experience, these manifestations do not occur or persist when hydroxychloroquine sulphate is used.Summary Three cases under treatment with chloroquine diphosphate are described-two of rheumatoid arthritis and one of disseminated lupus erythematosus.All three presented similar toxic reactions-namely, visual upset and bleachincg of the hair-occurring at similar stages in treatment.TIwo of the cases also had undue erythema of the skin on exposure to sunlight.The possibility that chloroquine interferes with the deposition of pigment or replaces normal pigment is suggested.These changes appear to be reversible.Cases 1 and 2 were shown to the North British Dermatological Society by one of us (J.L. C. D.).