Radioimmunoassay for the measurement of plasma renin activity (PRA) was performed in 43 normal Koreans and 45 patients with essential hypertension. Plasma samples were drawn in supine position in the morning and after upright posture for 4 hours. Urinary sodium excretion rates were measured in the concurrent 24 hour urine samples, as an index of their sodium balance. The results were as follows: 1. There was an inverse correlation between 24hr sodium excretion and PRA. The normal values of PRA in supine position ranged from 1.0 to 7.0 ng/ml/hr. when 24 hour sodium excretion were between 50 to 150 mEq. PRA in elderly tended to be low. 2. When stimulated by 4 hour upright posture, PRA increased by 2.6 times from the baseline value. 3. Of the 45 patients with essential hypertension, PRA was low in 10 cases (22.2%), normal in 28 cases (62.2%), and high in 7 cases (15.6%). 4. In the normal and high renin groups, who tended to be younger in ages, mean diastolic blood pressure and BUN were higher than in low renin group. Though hypertensive retinopathy and left ventricular hypertrophy in ECG were more prevalent in the former, no significant differences were noted as in the case of serum cholesterol. 5. There were 8 cases of cardiovascular complications (7 with cerebral vascular accident, 1 with myocardial infarction); 3 in low renin group (30%), 2 in normal renin (7.1%) and 3 in high renin group (42.9%). This figure indicated higher rate of cardiovascular complications in high renin groups, and lower rate in normal renin group. But the incidence of the complication was not significantly low in low renin group.

In an attempt to establish the diagnostic value of serum triiodothyronine and to correlate it with pathophysiologic mechanisms of thyroid hormones in various thyroid disorders, the author measured the serum triiodothyronine levels by means of radioimmunoassay and compared them with other thyroid function tests. This study was carried out in 152 cases with various thyroid functions; 28 cases as control, 51 cases of hyperthyroidism, 50 cases of euthyroidism and 23 cases of hypothyroidism. The results obtained were as follows: 1. The serum $T_3$ level in normal control group ranged between $131{\pm}34ng/dl$. 2. The serum $T_3$ levels ranged between $306{\pm}97ng/dl$ in hyperthyroidism $138{\pm}32ng/dl$ in euthyroidism and $60{\pm}27ng/dl$ in hypothyroidism. The significant differences between these groups were noted in this study. 3. In 5(9.9%) out of 51 cases with hyperthyoidism and 9(39.1%) of 23 cases with hypothyroidism, the serum $T_3$ were measured to be in normal range. Accordingly, the diagnostic value of the measurement of serum $T_3$ with hyperthyroidism was justifiable, but with hypothyroidism, it was less creditable than that of serum thyrotropin. 4. There was little significant difference between the diagnostic value of serum thyroxine and triiodthyronine levels in various thyroid disorders. However, $T_4/T_3$ ratio was decreased in patients with untreated hyperthyroidism because of more elevation of $T_3\;than\;T_4$. Consequently, the serum $T_3$ was more sensitive than $T_3$ in some thyroid disorders. 5. The serum $T_3$ level was much more sensitive and showed prompt shift in its level during the course of treatment on the patient with various thyroid disorders. And the measurement of serum $T_3$ was a good index for the evaluation of the thyroid function. From these results obtained, the measurement of serum $T_3$ by means of radioimmunoassay is a good way to understand the status of thyroid function with various thyroid disorders and evaluate the effects of the treatment given on these patients.

A knowledge of the wide ranges in shape of liver is important in the interpretation of hepatic scintigraphy as some variants may be easily confused with pathological abnormalities. In this study, the variations in shape in 250 cases of normal liver obtained by scintiphoto were categorized into 9 types by means of the arbitrary standard for classification. Following were the results; 1) Among 250 normal cases, type 5 was 118(47.2%) with the highest prevalence and type 3 was 2 (0.8%) with the lowest. 2) A high incidence of obesity was noted in type 1, type 4 and type 8. That of ideal weight was noted in type 2, type 5 type 6 and type 9. 3) A high ratio of cardiac impression in scintiphoto was noted in type 4, type 7 and type 8. That of square left lobe was noted in type 2, type 6 and type 9. Finally that of tailed left lobe was in type 4, type 7 and type 8.

It is a great value to find an early detection of involvement of ureteric obstruction in the carcinoma of cervix. Little or no knowledge of the condition of the kidneys or the lower urinary tract are able to elucidate by the biochemical studies such as blood nitrogen or urine creatinine in carcinoma of cervix. Findings of urography delineates the condition of urinary tract stasis in the renal pelvis and ureters, however, slight stasis maybe difficult to demonstrate. On the other hand isotope nephrography is accepted as a sensitive method to observe renal function especially in regarding to the excretory function of kidney. It was attempted to analysis the findings of urography conjunction with isotope nephrography in 50 cases of unselected patients with invasive carcinoma of cervix through pre and post irradiation follow up studies. Urography was done as a routine procedure and.analysed emphasising changes of collecting systems and ureter condition. Isotope nephrography was carried out by means of $15{\mu}ci\;I^{131}$-Hippuran injected intravenously and the curves were analysed as follows. Parameter were; time of maximum amplitude ($T_{max}$), half time of maximum amplitude ($T\frac{1}{2}$), Kac and Kex value calculated from these two parameters in Tobe's method. The excretion index by Aurell defines the ratio between the maximum activity and the activity measured on the slope of the third phase ten minites after it has reached its maximum. Results: 1. 28.8% had an abnormal IVP suggestive of ureteric involvement before irradiation therapy and the patient of stage III and IV were the great part. 2. 21.7% had abnormal findings of per-irradiation renogram whom showed normal IVP. The other group showed normal IVP which group also showed normal renogram prior irradiation. 3. The more severe the ureteric involvement, the change of excretion index was greater. 4. Even in stage I and II patient, abnormal renogram was revealed in 12 cases (39.4%) among 31 cases. 5. All cases of TAH showed abnormal findings of IVP and renogram. 6. No. definite change of renogram was obtained just after the irradiation therapy (point $A:8000{\sim}9000rads,\;B:5000{\sim}6000rads,\;Co:11000{\sim}13000rads$). Each 3 month follow up study was performed and comparing with preirradiation study which showed significant changes of excretion index of renogram were 42.8% in $6{\sim}9$ month follow-up and 75% in $9{\sim}12$ month, respectively. 7. It seems to be important to observe the parameter Kex and excretion index of renogram to determine early abnormality of kidney excretory function by means of post-irradiation follow up study.

53 patients with hyperthyroidism have been analyzed with special reference to therapeutic response to radioactive iodine ($^{131}I$) treatment. Mean effective half-life, 24 hour uptake rate and radiation dose of $^{131}I$ in hyperthyroid patients included in this study were respectively. 1. Mean effective half-life of $^{131}I\;was\;4.7{\pm}1.5$ days in the tracer dose and $5.0{\pm}1.5$ days in the therapeutic dose. 2. Mean 24 hour uptake rate of $^{131}I\;was\;72.7{\pm}11.1%$ in the tracer dose and $73.4{\pm}12.3%$ in the theapeutic dose. 3. Mean radiation dose of $^{131}I\;was\;5,319{\pm}2,648$ RAD as predicted and $5,692{\pm}2,843$ RAD as actual. A single dose of radioactive iodine treatment was satisfactory in 34 patients (radioiodine sensitive) and multiple doses of radioactive iodine treatments were required in 19 patients (radioiodine resistant). A radioiodine resistant group of patients with hyperthyroidism was distinctively characteristic in the following aspects. 1. Mean thyroid weight calculated in the resistant group ($63.9{\pm}14.0gm$) was significantly (p<0.01) greater than that of the sensitive group ($46.6{\pm}13.3gm$). 2. Mean 24 hour uptake rate of the tracer dose in the resistant group ($67.3{\pm}10.7%$) was significantly (p<0.01) lower than that of the sensitive group ($75.7{\pm}10.5%$). 3. Mean 24 hour uptake rate of the therapeutic dose in the resistant group ($68.5{\pm}13.7%$) was significantly (p<0.05) lower than that of the sensitive group ($76.1{\pm}10.9%$). 4. Mean predicted radiation dose, of $^{131}I$ in the resistant group ($3,684{\pm}1,745$ RAD) was significantly (p<0.01) lower than that of the sensitive group ($6,232{\pm}2,683$ RAD). 5. Mean actual radiation dose of $^{131}I$ in the resistant group ($4,100{\pm}1,691$ RAD) was significantly (p<0.01) lower than that of the sensitive group ($6,582{\pm}3,024$ RAD). 6. No significant difference was detected in terms of effective half-life of $^{131}I$ among the groups (p>0.05). 7. The average mean % difference of effective half-life, uptake rate and radiation dose measured following the tracer and therapeutic dose of $^{131}I$ were not statistically significant (p>0.05). Therefore effective half-life, uptake rate and radiation dose of the therapeutic dose of $^{131}I$ were readily predictable following the tracer dose of $^{131}I$. 8. It is concluded that the possibility of resistance to radioactive iodine treatment may be anticipated in patients with thyroid gland large in size and compromised $^{131}I$ uptake rate.