小便以气化为主，盖膀胱为州都，津液气化所出也。如闭而渴，则热伤上焦气分，宜理
肺气之化，生脉散加桔梗；闭而不渴，则热伤下焦血分，滋肾丸。中有湿热，亦不渴而闭，五苓
小便不利腹胀，火在下焦也，血化为水，必成中满，用细辛升少阴肾水，以降其火，然
后佐以利下药，其胀自消。
验案
一人大哭之后，小便不利而小腹痛。此乃悲哀伤肺，肺乃津液之化原，膀胱乃津液之腑
；化原伤，膀胱津液亦枯，故命火为患，小便不利而痛也。以甘寒保肺生津之药调之。
一人小便不通，渐成中满，腹坚大如石，腿胀出黄水，双睛突出，昼夜不睡，饮食不能
进。盖无阳则阴不长，无阴则阳不化。用滋肾丸。少时前阴火烧，便如泉涌而肿消。
一人年老，因入房忍而不泄，小便不利，诸药不效。此肾虚气滞血凝也，用土牛膝捣汁
，酒服二碗。小便出物长三寸，长六寸者二虫，遂愈。
一人小便不通，诸药不效。用吴萸、牛膝二味煎服，即通。
一人心思过度，房劳不节，小便涩痛，心脉浮散，左尺涩如刀割。此心遗热于小肠，以
致肾水枯涸，成阴虚火动也。用人参五钱，山药三两，茯苓、生地、枣仁各二两，元肉丸。
空心白汤送下。
北方黑色入通乎肾，开窍于二阴。二阴，大小便也，故肾司二便。二便不通，则肾水竭
，水竭则火燥。老人便燥多由于此。
验案
一人厥阴肿痛，小腹作胀，医用承气下之，又用五苓利之，遂大小便不通。予诊之，病
在厥阴，真寒证也。误用下利，阴盛隔阳，大便空者，小便利。用干姜、肉桂、枳壳各一钱，升
、柴各五分，吴萸三分，煎服，大便行；又用升麻、甘草梢各三分，吴萸二分，干葛、赤芍
、炮姜、肉桂、槟榔、木通各一钱，小便通而愈。
一人大便十日一解，小便短少，面上发癣。此阳气下陷，下焦化燥火也。用补中益气汤
倍归身，加红花、丹皮、黑栀子，升阳润燥，清下焦之热而愈。（张东扶曰∶前后分通，亦是一
法，世医杂施妄治，当以此为法。）
小便的通畅主要依赖于气化功能，因为膀胱是津液汇聚之处，也是津液通过气化作用排出的器官。如果小便闭塞且伴有口渴，说明热邪损伤了上焦的气分，应当调理肺气的化生功能，使用生脉散加桔梗；如果小便闭塞但不口渴，说明热邪损伤了下焦的血分，应使用滋肾丸。若体内有湿热，也会表现为不渴而小便闭塞。对于五苓散证出现的小便不利、腹胀，这是火邪位于下焦所致，血液受热煎熬化为水湿，必然导致腹部胀满，此时应用细辛提升少阴肾水，以降泄下焦之火，然后再辅以利尿药物，腹胀自然消除。
验案
有一人放声大哭之后，出现小便不利和小腹疼痛的症状。这是因为悲哀情绪损伤了肺气，肺是津液化生的源头，膀胱是贮存津液的腑器；源头受损，膀胱中的津液也随之枯竭，导致命门之火妄动，从而引起小便不利和疼痛。治疗采用甘寒性质的药物来保养肺气、生津液进行调理。
另一人小便不通，逐渐发展为腹部胀满，腹部坚硬肿大如石头，腿部肿胀流出黄水，双眼突出，昼夜无法入睡，饮食无法进服。这是因为没有阳气则阴精不能生长，没有阴精则阳气无法化生。使用滋肾丸。服药片刻后，前阴部位感觉如火烧般灼热，随即尿液如泉水涌出，肿胀随之消退。
还有一位老年人，因行房事时强忍精液不泄，导致小便不利，服用多种药物均无效。这是由于肾虚、气机阻滞、血液凝滞所致，使用土牛膝捣取汁液，用酒送服两碗。随后排出长约三寸的物体，以及两条长约六寸的虫体，病症遂愈。
又有一人小便不通，服用各种药物均无效。使用吴茱萸、牛膝两味药煎汤服用，小便即通。
还有一人心思过度，加之房事不节制，导致小便涩痛，诊见心脉浮散，左尺脉涩滞如刀割。这是心火遗热于小肠，致使肾水枯竭，形成阴虚火旺之证。用人参五钱，山药三两，茯苓、生地、枣仁各二两，制成元肉丸。空腹时用白开水送服。
北方黑色对应肾脏，与肾相通，开窍于前后二阴。二阴指大小便，因此肾主管二便。如果二便不通，则肾水枯竭，水枯竭则火势燥烈。老年人大便干燥多由此原因引起。
验案
有一人厥阴经部位肿痛，小腹胀满，医生误用承气汤攻下，又用五苓散利水，导致大小便完全不通。我诊断认为，病在厥阴，属于真寒证。误用攻下和利水之法，导致阴寒盛极格拒阳气，表现为大便虽空但小便利。使用干姜、肉桂、枳壳各一钱，升麻、柴胡各五分，吴茱萸三分，煎汤服用，大便得以通行；随后又用升麻、甘草梢各三分，吴茱萸二分，葛根、赤芍、炮姜、肉桂、槟榔、木通各一钱，使小便通畅而痊愈。
还有一人大便十天一次排便，小便短少，面部出现癣症。这是阳气下陷，下焦化燥生火所致。使用补中益气汤加倍当归身，加入红花、丹皮、黑栀子，以升举阳气、润燥，清泄下焦之热而痊愈。（张东扶评论说：前后分治通利，也是一种方法，世俗医生杂乱施治、胡乱治疗，应当以此为准则。）
The unobstructed flow of urine primarily depends on Qi transformation (Qi Hua), as the Bladder is the reservoir where fluids gather and from which fluids are excreted through the process of Qi transformation. If urinary retention occurs accompanied by thirst, it indicates that heat has damaged the Qi level of the Upper Jiao; in this case, one should regulate the transformation of Lung Qi, using Shengmai San (Generate the Pulse Powder) with added Jiegeng (Platycodon Root). If urinary retention occurs without thirst, it indicates that heat has damaged the Blood level of the Lower Jiao; Zishen Wan (Kidney-Nourishing Pill) should be used. If damp-heat exists within the body, it may also present as non-thirsty urinary retention. For cases of Wuling San syndrome presenting with difficult urination and abdominal distension, this is due to Fire located in the Lower Jiao; blood transformed into water by heat inevitably leads to fullness in the middle abdomen. In such instances, use Xixin (Asarum Root) to raise the Kidney Water of Shaoyin to descend the Fire, and subsequently assist with diuretic herbs; the distension will naturally subside.
Case Record 1
After a person wept loudly, they experienced difficult urination and lower abdominal pain. This was caused by grief injuring the Lung Qi. The Lung is the source of fluid transformation, and the Bladder is the fu-organ of fluids; when the source is injured, the fluids in the Bladder also dry up, causing the Ministerial Fire to become pathological, leading to difficult urination and pain. Treatment involved regulating with sweet-cold herbs that nourish the Lung and generate fluids.
Case Record 2
A patient suffered from urinary retention, gradually developing abdominal fullness. The abdomen became hard and swollen like stone, legs swelled with yellow fluid oozing out, eyes protruded, sleep was impossible day or night, and food intake ceased. This occurred because without Yang, Yin cannot grow; without Yin, Yang cannot transform. Zishen Wan (Kidney-Nourishing Pill) was administered. After a short while, a burning sensation arose at the anterior yin, followed by urine gushing forth like a spring, and the swelling subsided.
Case Record 3
An elderly person suffered from difficult urination after holding back ejaculation during sexual intercourse. Various medicines were ineffective. This was due to Kidney deficiency, Qi stagnation, and Blood coagulation. Juice extracted from crushed Tu Niuxi (Achyranthes Bidentata Root) was taken orally with wine, two bowls per dose. Subsequently, an object three cun long was discharged, along with two worms each six cun long, and the condition resolved.
Case Record 4
Another patient suffered from urinary retention, unresponsive to various medicines. Wu Zhu Yu (Evodia Fruit) and Niuxi (Achyranthes Root) were decocted and taken orally, resulting in immediate urination.
Case Record 5
A patient who overused their mind and lacked moderation in sexual activity experienced painful, difficult urination. The Heart pulse was floating and scattered, and the left Chi pulse was choppy and sharp like a knife cut. This indicated Heart fire transmitting heat to the Small Intestine, causing Kidney Water to dry up, resulting in Yin deficiency with hyperactive Fire. Ren Shen (Ginseng Root) 5 qian, Shan Yao (Dioscorea Rhizome) 3 liang, Fu Ling (Poria), Sheng Di Huang (Rehmannia Root), and Suan Zao Ren (Ziziphus Seed) 2 liang each were processed into Yuan Rou Wan (Longan Pill). Taken on an empty stomach with plain boiled water.
The black color of the North corresponds to the Kidney, communicating with it and opening into the two yin openings (anterior and posterior orifices). The two yin openings refer to urination and defecation; thus, the Kidney governs both. If both urination and defecation are obstructed, Kidney Water is exhausted; when Water is exhausted, Fire becomes dry and hot. Elderly people often suffer from dry stools due to this mechanism.
Case Record 6
A patient presented with swelling and pain in the Jueyin channel region and lower abdominal distension. Physicians mistakenly used Chengqi Tang (Bowel-Unblocking Decoction) for purgation and Wuling San (Five-Ingredient Powder with Poria) for diuresis, leading to complete obstruction of both urination and defecation. Upon diagnosis, I determined the disease was in the Jueyin channel and constituted a True Cold pattern. The erroneous use of purgatives and diuretics led to extreme Yin cold repelling Yang. Although the stool appeared empty, urination was free-flowing. Gan Jiang (Dried Ginger), Rou Gui (Cinnamon Bark), and Zhi Qiao (Aurantium Fructus) 1 qian each, plus Sheng Ma (Cimicifuga Rhizome) and Chai Hu (Bupleurum Root) 0.5 fen each, and Wu Zhu Yu (Evodia Fruit) 0.3 fen were decocted and taken orally, resulting in bowel movement. Subsequently, Sheng Ma (Cimicifuga Rhizome) and Gan Cao Gao (Licorice Tip) 0.3 fen each, Wu Zhu Yu (Evodia Fruit) 0.2 fen, Ge Gen (Kudzu Root), Chi Shao (Red Peony Root), Pao Jiang (Prepared Ginger), Rou Gui (Cinnamon Bark), Bing Lang (Areca Seed), and Mu Tong (Akebia Stem) 1 qian each were used, leading to patent urination and recovery.
Case Record 7
A patient had a bowel movement only once every ten days, scanty urination, and tinea on the face. This was due to sinking of Yang Qi and dryness-fire generation in the Lower Jiao. Buzhong Yiqi Tang (Middle-Supplementing Qi-Boosting Decoction) with doubled Dang Gui Shen (Angelica Sinensis Root tip) was used, adding Hong Hua (Safflower), Dan Pi (Moutan Cortex), and Hei Zhi Zi (Black Gardenia Fruit) to raise Yang, moisten dryness, and clear Lower Jiao heat, resulting in recovery. (Zhang Dongfu commented: Treating the anterior and posterior orifices separately to promote unobstruction is also a valid method. Modern physicians often apply chaotic and erroneous treatments; this case should serve as a standard.)